$y=2^{-\log _2\left(x^3-5\right)}$, then $\frac{d y}{d x}$ is
Answer & explanation
Correct answer: option 1
$y=2^{\log _2\left(1 /\left(x^3-5\right)\right)}=\frac{1}{x^3-5}=\left(x^3-5\right)^{-1}$
$\frac{d y}{d x}=-1\left(x^3-5\right)^{-2} \times 3 x^2=\frac{-3 x^2}{\left(x^3-5\right)^2}$
Hence (1) is correct answer.