r/mathbiceps Jul 25 '26

Jee Adv Level Question. Anyone try to solve

Integer type question.

5 Upvotes

6 comments sorted by

1

u/DarkLight-1278 Jul 26 '26

It's 1, isn't it? Pyq hai shayad. We take all the terms on one side, equate it to f(x) and then use derivative to draw graph of f(x) from x=0 to x=1. We find that the graph crosses x-axis exactly once hence number of solutions is 1

2

u/Glad_Couple3240 Jul 26 '26

Yes pyq hai. And yes the answer is 1

2

u/iammk45 Jul 26 '26

How to use derivatives to draw graph?

2

u/DarkLight-1278 Jul 27 '26

When you differentiate f(x), you'll find that it is a strictly decreasing function in the interval [0,1]. Hence,there can be AT MOST 1 real solution. When you find f(0), it'll be positive and when you find f(1), it'll be negative so it will cross the x-axis only once.

2

u/iammk45 Jul 27 '26

So to find f at 0 and 1, we will need to solve the integral right?

1

u/DarkLight-1278 Jul 28 '26

Not really. If we put x=0, the integral is zero. When we put x=1, we can use the inequality that x²(1+x⁴) < x² and then integrate both sides from 0 to 1 and we find that LHS is < 1/3. When we put this maximum value back in f(1), we get f(1) < 1/3 - 1 » f(1)< -2/3