1, y = xe x, domain: x∈R

When x∑(-∞,-1), the function monotonically decreases; when you

The function y = xe x has a minimum value and y=- 1/e has no maximum value.

2. the function y = x/e x, and the domain is x ∈ r.

X∈(-∞, 1), y`>0, the function is monotonically increasing; X∈( 1, +∞), y`<0, the function is monotonically decreasing.

There is a maximum value, y= 1/e, and there is no minimum value.

3. the function y = e x/x, and the domain x≠0.

When x∈(-∞, 0) and y ′ < 0, the function decreases monotonically; When x∈(0, 1) and y ′ < 0, the function decreases monotonically; When x∈( 1, +∞), the function of y ′>0 is monotonically increasing.

4. Function y=xlnx, domain: x∈(0, +∞)

When x ∈ (0, 1/e) and y ′ < 0, the function monotonically decreases; When x∑( 1/e, +∞), the function of y ′>0 is monotonically increasing.

5，y=x/lnx。 Domain: (0, 1)∞( 1, +∞)

When x ∈ (0, 1) and y ′ < 0, it decreases monotonically; When x∈( 1, e), y`.

6. The function y=lnx/x, and the domain is x∈(0, +∞).

When x∈(0, e), y` >; 0, the function is monotonically increasing; When x∈(e, +∞), y ′