已知-1已知-1
已知-1-10|x+1|=x+1x
-1|x+1 |=x+1|x-2| =2-x|3-x |=3-x|4-2x | =4-2x |x+1 |+ |x-2 |- |3-x |+ |4-2x | =x+1+2-x-3+x+4-2x=4-x
4-x