Medium INTEGER +4 / -1 PYQ · JEE Mains 2025

Let $f$ be a differentiable function such that $2(x+2)^2 f(x)-3(x+2)^2=10 \int_0^x(t+2) f(t) d t, x \geq 0$. Then $f(2)$ is equal to ________ .

Answer (integer) 19

Solution

<p>$$\begin{aligned} &\text { Differentiate both sides }\\ &\begin{aligned} & 4(x+2) f(x)+2(x+2)^2 f^{\prime}(x)-6(x+2)=10(x+2) f(x) \\ & 2(x+2)^2 f^{\prime}(x)-6(x+2) f(x)=6(x+2) \\ & (x+2) \frac{d y}{d x}-3 y=3 \\ & \int \frac{d y}{d x}=3 \int \frac{d x}{x+2} \\ & \ln (y+1)=3 \ln (x+2)+C \\ & (y+1)=C(x+2)^3 \\ & f(0)=\frac{3}{2} \\ & f(2)=19 \end{aligned} \end{aligned}$$</p>

About this question

Subject: Mathematics · Chapter: Differential Equations · Topic: Order and Degree

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