JEE MAIN - Mathematics (2024 - 8th April Evening Shift - No. 23)

If $$\int \frac{1}{\sqrt[5]{(x-1)^4(x+3)^6}} \mathrm{~d} x=\mathrm{A}\left(\frac{\alpha x-1}{\beta x+3}\right)^B+\mathrm{C}$$, where $$\mathrm{C}$$ is the constant of integration, then the value of $$\alpha+\beta+20 \mathrm{AB}$$ is _________.
Answer
7

Explanation

$$\begin{aligned} & I=\int \frac{1}{\sqrt[5]{(x-1)^4(x+3)^6}} d x \\ & \frac{x+3}{x-1}=t \Rightarrow d x=\frac{-4}{(t-1)^2} d t \Rightarrow x=\left(\frac{3+t}{t-1}\right) \\ & \Rightarrow(x-1)^4(x+3)^6=(x-1)^5(x+3)^5\left(\frac{x+3}{x-1}\right) \\ & I=\int \frac{\frac{-4}{(t-1)^2} d t}{t^{1 / 5}\left(\frac{3+t}{t-1}-1\right)\left(\frac{3+t}{t-3}+3\right)} \\ & I=\int \frac{-4 d t}{t^{1 / 5}(16 t)}=\frac{5}{4}\left(\frac{x-1}{x+3}\right)^{1 / 5}+c \end{aligned}$$

Comparing,

$$\begin{aligned} & \Rightarrow A=\frac{5}{4}, B=\frac{1}{5}, \alpha=1, \beta=1 \\ & \Rightarrow \alpha+\beta+20 A B=1+1+20 \times \frac{5}{4} \times \frac{1}{5}=7 \end{aligned}$$

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