f(x)=x³-6x+5f‘高扮(x)=3x²-6=0x=±√戚困灶2单调区间(-∞,-√2),[-√2,√2),[√2,+∞)x=-√2时f‘'(x)=6x<0,极值f(-√2)=(-√2)³-6(-√2)+5=4√2+5x=√2时f‘'尺枝(x)=6x>0,极值f(√2)=5-4√2