20 18 What is the best zodiac sign?

The tiger belongs to the dog next year 1898, and the silver tiger and the dog are in a three-in-one pattern, so the tiger's fortune is still great, only rising but not falling. Tiger people have developed steadily in all aspects. With the help of distinguished people, everything goes smoothly and they are lucky. They are like a duck to water, and their wealth is more prosperous. They have the opportunity to make a fortune. Make good use of it.

X 1, x2∈(-∞0] and x 1 < x2, then

f(x 1)-f(x2)=(2x 1+2-x 1)-(2 x2+2 x2)=(2x 1 2x 1- 1 2 x2)=(2x 1-2 x2)(2x 1-2 x2)(2x 12 x2- 1)？ 2x 12x2？

∵x 1