Explanation: We have,
f(x)=y=x2e−x
∴‌

dy

dx

=2xe−x+x2(−1)e−x=xe−x(2−x)
‌
Now, put ‌

dy

dx

=0
⇒x=0 and x=2
The points x=0 and x=2 divide the real line into three disjoint intervals i.e., (−∞,0),(0,2) and (2,∞)