
Nitin P. answered 06/28/20
Machine Learning Engineer - UC Berkeley CS+Math Grad
To find the critical points, we need to take the derivative and set it equal to 0. we have:
f'(x) = e-2x - 2xe-2x = 0
e-2x(1 - 2x) = 0
x = 1/2
Since f'(x) > 0 for x < 1/2 and f'(x) < 0 for x > 1/2, the point (1/2, 1/(2e)) is a local maximum. Now, we take the derivative again and set it equal to 0 to find the points of inflection. We have:
f''(x) = -2e-2x - 2e-2x + 4xe-2x = -4e-2x + 4xe-2x = 0
4e-2x(x - 1) = 0
x = 1
The point of inflection is therefore (1, e-2). Since f''(x) > 0 for x > 1, f is concave up for (1, ∞), and since f''(x) < 0 for x < 1, f is concave down for (-∞, 1).