如题所述
f(X)=|X^2-4X-5|,
当X^2-4X-5>0,即(X-5)(X+1)>0,X<-1或X>5时,
f(X)=(X-2)^2-9,
当-1≤X≤5时,
f(X)=-(X-2)^2+9,