Question

The interval in which $y=x^2{e}^{-x}$ is increasing is

• A. $(-\infty ,\infty )$
• B. $(-2,0)$
• C. $(2,\infty )$
• D. $(0,2)$

Answer 1

Answer: (D)

$f^1(x)>0\Rightarrow x^2\cdot e^{-x}\cdot (-1)+e^{-x}\cdot 2x>0$