f(x)=ax²+x-a
當(dāng)a=0時(shí),f(x)=x,在區(qū)間[-1,1]上最大值為M(a)=1
當(dāng)對(duì)稱軸x=-1/(2a)<=-1即0當(dāng)對(duì)稱軸-1<=x=-1/(2a)<0即a>=1/2時(shí),x=1時(shí)取得最大值,M(a)=f(1)=1
當(dāng)對(duì)稱軸0
a<=-1/2時(shí),M(a)=-a-1/(4a)>=2√[-a*1/(-4a)]=1
a>=-1/2時(shí),M(a)=1
當(dāng)-1<=a<=1時(shí),a=-1時(shí)M(a)取得最大值為1+1/4=5/4