The interval in which the function $g(x) = x^2e^{-x}$ is increasing is: |
$(-∞, ∞)$ $(-2, 0)$ $(2,∞)$ $(0, 2)$ |
$(0, 2)$ |
The correct answer is Option (4) → $(0, 2)$ Given function $g(x)=x^2 e^{-x}$ Differentiate w.r.t. $x$ $\frac{dg}{dx}=2x e^{-x}+x^2(-e^{-x})$ $=e^{-x}(2x-x^2)$ $=e^{-x}x(2-x)$ Since $e^{-x}>0$ for all $x$, sign of $\frac{dg}{dx}$ depends on $x(2-x)$. $x(2-x)>0$ when $0<\text{ x }<2$. Increasing in $(0,2)$ |