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← JEE Main 2022 · 30 Jun · Shift 1
MathematicsInteger+4 / -1Question 25 of 90

JEE Main 2022 · 30 Jun · Shift 1, Mathematics question 25

Let f(t)=∫0tex3(x8(x6+2x3+2)2)dxf(t)=\displaystyle\int_0^te^{x^3}\left(\frac{x^8}{\left(x^6+2x^3+2\right)^2}\right)dx. If f(1)+f′(1)=αe−16f(1)+f'(1)=\alpha e-\dfrac16, then the value of 150α150\alpha is equal to ______.

Answer and worked solution

Official answer: 16

Antiderivative. ddx[ex33(x6+2x3+2)]=x8ex3(x6+2x3+2)2\dfrac d{dx}\left[\dfrac{e^{x^3}}{3(x^6+2x^3+2)}\right]=\dfrac{x^8e^{x^3}}{(x^6+2x^3+2)^2}, so f(1)=e15−16f(1)=\dfrac e{15}-\dfrac16.

Derivative. f′(1)=e25f'(1)=\dfrac e{25}.

Sum. α=115+125=875\alpha=\frac1{15}+\frac1{25}=\frac8{75}, so 150α=16150\alpha=16.

Answer: 16