Can YOU Find f(2) Faster? Calculus Tricks They Skip in Class | MOA Lesson 70

Aug 27, 2026 7:20 AM

Hey Math Fans!

In response to frequent requests from students, we structured a fully rigorous, step-by-step resolution that addresses every analytical subtlety of this problem.

Here is our problem statement:
Let f be a continuously differentiable function defined on the positive real numbers, such that f(1)=2.

Suppose f satisfies the condition: the limit as t approaches x of the quantity t squared times f of x, minus x squared times f of t, all divided by t minus x, equals 1, for all x >0

Can YOU evaluate the exact value of f(2)?

For a detailed step-by-step solution, watch MOA Lesson 70, linked below:

https://youtu.be/IUid51tEqwM

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The Math Olympiad Academy Team

3 days ago | Likes 1 Dislikes 0

This was written by a virgin robot

3 days ago | Likes 3 Dislikes 0

(Who is also megaloads smarter than me)

3 days ago | Likes 2 Dislikes 0

The best way to solve a problem like this is to already know the answer

3 days ago | Likes 1 Dislikes 0

First, turn the limit into a standard linear differential equation form. then find f(x), then replace x by 2 to find the value of f of 2. It is easy.

3 days ago | Likes 1 Dislikes 0

It's a Feynman quip he would use in lectures referring to differential equations. Nevermind.

3 days ago | Likes 1 Dislikes 0

The exact value of f(2) is 3.

3 days ago | Likes 2 Dislikes 0

No, it is not 3, first solve the problem and turn the limit into a standard linear
differential equation form. then find f(x), then replace x by 2 to find the value of f of 2.

3 days ago | Likes 1 Dislikes 0

I did that. Then converted back to standard linear, then did a general solution. Using a initial condition to get 3 my constant violates the boundary condition f(1)= 2.

But I've been smoking a lot of weed tonight so there's that. I'll

3 days ago | Likes 1 Dislikes 0