Duration 3:30

A tricky exponents problem from the UK

by MindYourDecisions

245 349 watched

0

9.5 K

Published 29 May 2021

Students in the UK faced a similar question to this one. Don't give up--U can solve it! Adapted from https://www.reddit.com/r/HomeworkHelp/comments/de402k/gcse_edexcel_further_math_how_would_you_solve_for/ Subscribe: /user/MindYourDecisions Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for sales. (As an Amazon Associate I earn from qualifying purchases.) This has no effect on the price for you. My Books (worldwide links) https://mindyourdecisions.com/blog/my-books/#worldwide My Books (US links) Mind Your Decisions: Five Book Compilation https://amzn.to/2pbJ4wR A collection of 5 books: "The Joy of Game Theory" rated 4.2/5 stars on 189 reviews http://amzn.to/1uQvA20 "The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" rated 3.9/5 stars on 16 reviews http://amzn.to/1o3FaAg "40 Paradoxes in Logic, Probability, and Game Theory" rated 4/5 stars on 28 reviews http://amzn.to/1LOCI4U "The Best Mental Math Tricks" rated 4.1/5 stars on 53 reviews http://amzn.to/18maAdo "Multiply Numbers By Drawing Lines" rated 4.1/5 stars on 22 reviews http://amzn.to/XRm7M4 Mind Your Puzzles: Collection Of Volumes 1 To 3 https://amzn.to/2mMdrJr A collection of 3 books: "Math Puzzles Volume 1" rated 4.4/5 stars on 67 reviews http://amzn.to/1GhUUSH "Math Puzzles Volume 2" rated 4.2/5 stars on 19 reviews http://amzn.to/1NKbyCs "Math Puzzles Volume 3" rated 4.2/5 stars on 15 reviews http://amzn.to/1NKbGlp 2017 Shorty Awards Nominee. Mind Your Decisions was nominated in the STEM category (Science, Technology, Engineering, and Math) along with eventual winner Bill Nye; finalists Adam Savage, Dr. Sandra Lee, Simone Giertz, Tim Peake, Unbox Therapy; and other nominees Elon Musk, Gizmoslip, Hope Jahren, Life Noggin, and Nerdwriter. My Blog https://mindyourdecisions.com/blog/ Twitter https://twitter.com/preshtalwalkar Merch https://teespring.com/stores/mind-your-decisions Patreon https://www.patreon.com/mindyourdecisions Press https://mindyourdecisions.com/blog/press

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Mathematics

Math

Maths

Riddle

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Puzzle

Math puzzle

Comments - 1060

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@davidhiggins51323 years ago " let' s take a look at 3 to the power of x. #39; u' can solve it"
" uh no i can' t. Oh that u" 252
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@jagmarz3 years ago I think it' s more satisfying to say the answer is log3(5) 1. 837
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@fongalex66393 years ago Thanks and this is one of the easiest question in this channel! 831
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@omerbulduk66283 years ago This is the first question that i solved in this channel before watching the solution and today is my birthday: 315
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@jorgetodeschini54463 years ago I love it when he throws in an easy question every now and then! 2
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@xactlyinc3 years ago I think taking log3 gives a more beautiful answer since we are dealing with two 3' s. 56
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@daanvoets41253 years ago Before i found your channel i felt confident about my math skills. 5
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@benzored3 years ago I wish i had seen this video while i was still teaching college algebra. It' s a great way to incorporate all the skills from that class. 16
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@tony26373 years ago Almost the same way but my answer is log3 (5/3) 105
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@adityayalagoor20103 years ago This was one of fewest questions on this channel, that i could solve. Good one. 7
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@Ryan_but_the_name_was_taken3 years ago Its been 13 years since ive done any form of math like this but it all comes back somewhat when seeing familiar style equations. 1
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@ponnshaa20073 years ago Learnt logarithmic stuff a few days ago and this was a good way to test myself. Thanks. 5
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@vidblogger123 years ago Dang, here i thought i was special for getting this one. Looks like it' s actually not that hard to spot the quadratic. 27
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@tjohnson40623 years ago I' ve been watching your videos for a while now and i have to say that i might not be any better with math but i am about 300% more humble. I think . ...Expand 2
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@sallychi84063 years ago Theanswer to 3^x =3 should be 1 + (i / ln 3) since ln(1) i. 25
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@bambi38863 years ago Whenever this type of question came out in exam. I' d give up immediately. But thank you for making this video. I' m enlightened. 3
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@lady0shady3 years ago Wow, i' m so glad that i still remember basics and solved this one. 2
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@sohangundoju89403 years ago Without even any background iitians are used to seperating and solving it as a normaleasy for most mpc students. 41
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@overlordprincekhan3 years ago This is the type of maths that i could solve very easily. 12
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@stevebitar70123 years ago Thanks presh! Nice problem. Q. Why stop at real values of x? The complex solution is fun to solve for: x=i(pi)/ln3 +1 great review of logarithms for me. 1
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@Robi20093 years ago " you can solve it"
no, i can' t
" u is equal to 3^x"
hahaha, very funny: /. 28
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@mohamedamr13513 years ago Thanks for the wide range of questions.
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@user-dp9yn7zf4l3 years ago Yr10 math teacher should show this to their student
a brilliant question covers both quadratic and logarithm. 2
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@charliehe45423 years ago I see thathas been posting more easier questions recently as confidence boosters. Thanks.
a more easier solution is to mu the equation by 3 and you have 3^(2x+2) + 4*3^(x+1) 45 = 0. Then substitute 3^(x+1) y, we have y^2 + 4y - 45 = 0, which we can factorize by simply eyeballing. ...Expand 4
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@advaymayank14103 years ago I have been watching your videos and could solve this one with ease. Thankyou for these videos! 2
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@lighthouse37313 years ago The only question of this youtuber that i can solve without watching the entire video. 1
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@akhladmehboob3 years ago Solved it without watching first time feeling proud thanks for these problems. 1
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@samuelpierce99623 years ago Once you recognize it' s a quadratic you just have to work out the algebra. I used log base 3 though. Fun puzzle. 2
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@nyfyre37683 years ago We did this in math class on tuesday!
not this exact problem, but this concept. 1
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@GamingDragon073 years ago When you realise it' s u can solve it and not you can solve it. 9
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@markgillespie39713 years ago Nice problem. I did it slightly differently, multiplied through by 3 at the start then used u = 3^(x+1) as substitution.
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@DanielWalvin3 years ago At , taking log_3 of both sides instead of ln:
log_3(3^x) = log_3(5/3).
x log_3(3) = log_3(5) - log_3(3).
x = log_3(5) - 1.
Less likely to be able to use your calculator on it to get a numerical answer, but simpler and looks better. .. ...Expand 1
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@doudouherve12483 years ago Thanks for this. I just need to know which application are you using to make this kind of video.
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@neutron4173 years ago The trend of algebra questions in this channel is towards the easier side especially this one was one of the easiest. 1
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@yurineuro90483 years ago Really liked the smooth graphical illustration. Does anyone know what type of software has been used? 2
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@noogler1233 years ago I see every equations as a quadratic equations first. 50
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@guobinsee69163 years ago In malaysia already existed this type of question more than 10 years, can refer past year of spm add maths questions/ chapter name: indices and logarithm.
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@shaparmy4653 years ago So, i am a bit confused here. When can we use natural log and when is log must be used? If these two terms are used for this question, will both result in the same answer? Thanks! 1
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@marx57403 years ago Hey, i wish you can tell in the beginning of the problem on what mathematical knowledge i need to solve it. I wanna solve these problems but i haven' t learned about it yet.
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@tonyennis17873 years ago What mental leap made you choose the `u=3x` technique (starts around ) ? That's what I missed. manipulating the symbols I can do. But knowing which technique. not so much. .. ...Expand
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@szyszak33383 years ago I am from poland and i am in highschool.
such equations are here very popular and we do them normally.
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@takeshiasahi54943 years ago Dono. I just went rogue and put x= 1/2. Kinda worked at integer level but not at decimal, extra 0. 9 was left ) how ironic. 3
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@parthosaha41703 years ago The first problem i was able to solve of this channel. 1
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@pomi63203 years ago Through my thesis, doing this the actually medieval mathematical way and the way that o was taught by cambridge international advanced examination in britain. It will be 0. 73516. Log3(3 square root 2 then -2) 0. 73516. 1
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@ardnys353 years ago That one was simple but it' s always satisfying when these stuff turn into quadratics. I have been solving quadratics for years and it' s still satisfying. 5
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@jacobzinka74013 years ago As soon as i saw the +1 to the 2x exponent, i knew the answer. 1
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@marseille32523 years ago About to take my add maths exam and am glad that i could solve this.
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@adityaseth_7773 years ago Already solved without watching. But nice one. Your videos are really great. 38
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@urkanchha3 years ago These are the very common problems asked in our middle school every annual exam.
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@LucasPreti3 years ago Thanks for the thumbnail, i managed to do it in my head. 2
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@sumansharma98573 years ago We used to solve these type of quadratic equations in 9th standard. I considered 3 to the power x as a. We used to solve so many sample exam papers that it came so naturally.
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@scoobydoo753 years ago If we are taking square on both sides i. E. U^2 =3^x)^2 so on r. H. S, it should become 9^2x because we took square of (3^x) as a whole. I am a bit confused at that point. 1
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@DARKNESSrbg3 years ago This is one of the easiest problems on this channel and i didnt even know where to get started.
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@muhammadsiddiqui22443 years ago Did it instantly, just because studied this in college, reducible to the quadratic form"
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@muradmuhammed94413 years ago You are wonderful thanks for your efforts.
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@abhilashpatel30363 years ago The only question i was able to crack on this channel. 1
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@LocalDandrew923 years ago I made my own question but i don' t know the answer.
a game of chess is played with a 500 elo human and a 550 elo bot. The timer is infinite. What is the expected number of moves the game lasted? 1
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@sgcomputacion3 years ago Thank you for giving me the opportunity to believe that i am an excellent mathematician.
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@rishiaman22883 years ago I treated the 3 as z and used the quadratic equation. 16
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@rameshkr6490last year Why do you take natural log of both sides instead of any other log such as log base 10? They both have the same results after all. Thank you.
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@thomjanssen81153 years ago The last is much more easy! Just applying the rules: gives x = log3(5/3) 0. 465 the eact same answer. 1
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@weebcells23913 years ago Thanks for the questionn
it was the easiest one i ever found on your channel.
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@madhurawat1553 years ago I was able to solve it till 3^x = 5/3, i just haven' t studied log yet. 6
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@lapprentice3 years ago Lemme guess while i' m driving: substitution 3^x as another abstract unknown then solve standard quadratic. 2
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@piman92803 years ago Hallelujah - presh finally called it " the quadratic formula! "
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@niccolocervelli75693 years ago I actually did it, now i' m feeling smart. 1
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@omplayschess3 years ago Omg you are a pro man. I watched him accidentally and now i watch him regularly.
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@christianvanderstap62573 years ago Dear lord, i have forgotten a lot over the years. 3
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@mushfikaikfat3 years ago perhaps one of the easiest problems you' ve solved so farxd
i' ve already solved it without watching
love from bangladesh. 2
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@MrRobbertJ3 years ago I have a riddle for you:
Two trains, Train A and Train B, simultaneously depart Station A and Station B. Station A and Station B are 252.5 miles apart from each other. Train A is moving at 124.7mph towards Station B, and Train B is moving at 253.5mph towards Station A. If both trains departed at 10:00AM and it is now , how much longer until both trains pass each other? .. ...Expand
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@andyiswonderful3 years ago Easy one. Did it exactly like you did.
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@shilamondal19403 years ago It is a simple one but good for learning quadratic equations.
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@atulkumar-lx6hg3 years ago This cn be solved by taking 3pwerx as y and the eq will be reduced in quadratic form 3 y square + 4y-15=0
which gives two value and the -ve will be discarded only +ve will be taken.
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@creativators96753 years ago I think it' s the 2nd or 3rd question of quadratic equation chapter. 3
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@muh.rofiadhimrajab83753 years ago 3^x = 5/3
using the logaritma form
a^b = c
a log c = b (a is basis)
then, the solution is
x = 3 log (5/3)
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@abhishekpatil10632 years ago The values of x are
and x = log.
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@dheerajsamota51943 years ago This question is like the basic question which u are taught in quadratic equations in topicif u are preparing for jee.
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@aaryunik3 years ago Satisfaction: when you are able to solve aproblem before moving on to the video.
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@georgepapakostas72923 years ago I literally figured it out by completing the square which was more complicated but yielded the same result. The only part i couldnt figure out was the log cause ive never learned it! So close lol!
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@chris-ph6so3 years ago You can' t write that 3(3^2x) 3^2x+1 because if we multiple it out we got just 3^13^2x and we don' t add those exponents we multiply thm so that would just be 2x.
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@Jason-ot6jv3 years ago Easy yet satisfying to solve. Very nice lol.
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@xeus3 years ago Others might' ve mentioned this already, butand so you can simplify the answer towhile you could represent ln(5)/ln(3) log from 5, i think the answer with natural log and integers is the most beautiful one. ...Expand
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@louisd957143 years ago Not too sure why i even watch these videos when i canot solve any of them. To those of you who can, good for you!
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@d4django3 years ago Thank you. You solved it exactly just like i did. But instead of ' u' i used ' y' and instead of taking ln, i took log to the base 3. Which . ...Expand 6
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@joshuaprice13 years ago Please could you do a series for people who aren' t quite as clever where you give us hints as how to find the answer. I could have done every equation . ...Expand
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@awaanmustafa22573 years ago Jee aspirants solve almost every logarithmic and exponential equations by this method. 1
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@lexus_bkl3 years ago The same approach was done by you in your one of your videos: 4^x + 6^x = 9^x. 1