Xiaohui, who is good at constantly improving mathematics learning methods, finds that reviewing and reflecting on solving mathematics problems is more effective. One day, Xiaohui has a 20-minute self-

Xiaohui, who is good at constantly improving mathematics learning methods, finds that reviewing and reflecting on solving mathematics problems is more effective. One day, Xiaohui has a 20-minute self-study class. Solution: (1) is given by graph 1

When,,

Solve,.

(2) From Figure 2, when, set.

When,

,

.

That is.

When.

therefore

(3) Let Xiaohui take a minute to review and reflect, and the total benefit of learning is,

Then the time she spends solving the problem is minutes.

When.

When.

When.

It decreases with the increase of, so when.

To sum up, when, at this time.

A: When Xiaohui spends 4 minutes reflecting and 16 minutes solving problems, the total learning benefit is the greatest.