f(x)=|x-2|-|x-5|求证-3≤f(x)≤3和解不等式f(x)≥x²-8x+15

问题描述:

f(x)=|x-2|-|x-5|求证-3≤f(x)≤3和解不等式f(x)≥x²-8x+15
明早7:30前请回答.

(1)证明:∵函数f(x)=|x-2|-|x-5|
(x