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← JEE Main 2026 · 2 Apr · Shift 2
MathematicsSingle correct+4 / -1Question 19 of 75

JEE Main 2026 · 2 Apr · Shift 2, Mathematics question 19

Let f(x)=∫(16x+24x2+2x−15)dxf(x)=\displaystyle\int\left(\frac{16x+24}{x^2+2x-15}\right)dx. If f(4)=14log⁡e(3)f(4)=14\log_e(3) and f(7)=log⁡e(2α⋅3β)f(7)=\log_e\left(2^\alpha\cdot3^\beta\right), α,β∈N\alpha,\beta\in\mathbb N, then α+β\alpha+\beta is equal to :

Choose one option
Answer and worked solution

Official answer: C

Partial fractions. 16x+24(x+5)(x−3)=7x+5+9x−3\dfrac{16x+24}{(x+5)(x-3)}=\dfrac7{x+5}+\dfrac9{x-3}, so f=7ln⁡∣x+5∣+9ln⁡∣x−3∣+Cf=7\ln|x+5|+9\ln|x-3|+C.

Constant. f(4)=7ln⁡9+C=14ln⁡3f(4)=7\ln9+C=14\ln3, so C=0C=0.

Value. f(7)=7ln⁡12+9ln⁡4=32ln⁡2+7ln⁡3f(7)=7\ln12+9\ln4=32\ln2+7\ln3, so α+β=39\alpha+\beta=39.

(C)