@Universee_201

4 raised to 4 is 256 right??

@YarGnawh

this lambert W function feels like a cheat code.

@aubrey1008

I don't think anyone is learning the Lamber function in high school.  Therefore not sure this would be on any college entrance exam.

@Vega1447

There is no Harvard Entrance Exam and no need to reference the Lambert W function.  The solution is between 3 and 4. Just take the log of each side : t log t=2log 7. Then use a couple of iterations of Newton's method to solve: t=(t+2*log(7))/(1+log(t)). Solution is approximately 

   3.278031523596059

@Name-ps9fx

I, lacking any Calculus skills, use the "Artillery" method.
T^t = 49
3³ = 27
4⁴ = 256
I have now "bracketed" the range, within which is the target. Now we just increase the minimum range (3) by tenths:

3.2^3.2 = 41.35
3.3^3.3 = 51.42

This is the new bracket, we then adjust our estimations by hundredths:

3.27^3.27 = 48.15
3.28^3.28 = 49.21

We then continue finding each range, and increasing the next decimal until we derive adequate accuracy required by the question.

😊

@jeremybearimy_0

3^3=27 (low)
4^4=256 (high)
3.5^3.5 (high)
3.25^3.25 (low)
3.275^3.275 (low)
3.28^3.28 (high)
3.2775^3.2775 (low).... quickly got to ~3.2781, but could keep going for more accuracy

@sparegod149

My dumbass really thought 7⁷ =49 .

@mrrandom.

Please use ln instead off log as log with no base is used for base 10

@UditPradeep_TOURBILLIONW16

To solve \(T^T = 49\), take natural log on both sides: \(T \ln T = \ln 49\). Since \(\ln 49 ≈ 3.8918\), solve \(T \ln T = 3.8918\). This transcendental equation gives \(T ≈ 3.3\) as the approximate solution. Exact value needs numerical or graphical methods.

@mikeburns6603

There are dozens of videos similar to this where the solution is always the W function.  They're trying to make the W function into one of the primary functions, such as ln, exp, sin, cos, etc.  But one could always create a problem for which a Jessel function is the solution.  If you do it over and over, then you can prtend like Jessel functions should be included in the list of primary functions.

@micahmeneyerji

0:39 4^4 is not 64!

@gauisameme8697

pls use ln() since log is mostly used for 10 asw

edit: i read about it more and found out log(x) has many bases including e, 10 and 2
- comp science uses 2 since binary has 2 digits 
- higher levels of maths / physics mostly use base e 
- highschool math & chem use base 10 (e.g when calculating pH) and many calculators have log(x) as base 10

tldr; the meaning of log depends on the application/context, but using ln() makes it more clear (esp for high school students)

@MisterJeffy

This would have more value to more people if you explained the basics of the steps you took to solve it.

@fabricer9623

OR you can use the well known  Wilson L function, the main property of which is L(x^x) = x. Which yields x = L(49) = 3.278 approximately.

@tschantz

Looking for the W button on my calculator…

@vishalmishra3046

t^t is a continuous, differentiable and monotonically increasing function . Since 3^3 = 27 < 256 < 4^4, therefore 3 < t  < 4.
Therefore, apply Newton's method to get t = 3.278031523596059366055947260535156966261673645376747543163853771604845412696293875445828810498337202... (100+ places of decimal accuracy with near zero effort).
No weird / less-known or one-off or unusual (including Lambert) function required to solve this entire class of problems to any arbitrary desired accuracy. [ How would you calculate Lambert W function anyway ? ]

@Cricketlover-e1y4l

Lambert W Function
The Lambert W function, also known as the Omega function, is a mathematical function used to solve equations in which the variable appears both inside and outside of an exponential function or logarithm.

Definition
The Lambert W function is defined as the inverse function of:

f(W) = We^W

@akr1011

t lnt = ln 49
Lnt= 49/t 

Plot graph, get intersection, simple 
Ans t= 3.278

-althaf 
Calicut

@jimmcneal5292

Honestly they should explicitly tell about Lambert W function, using it is quite random, and unless student specifically knows it he'll likely invent some other function(like V=lnW) to solve the equation

@ManishJoshi-o5u

t^t = 49
t.ln(t) = ln(49)
t = ln(49)/ ln(t)

since 3^3 = 27 and 4^4 = 256, so 3<t<4

use 3 as initial guess. 
use any numerical method like fixed point iteration method, Nr method etc.

to do this with fixed point iteration method
save 3 as ans in calculator.
type,  ln(49)/ln(ans)
and repeatedly spam '=' , you will get 3.278..