
已知x属于【-3,2】 求f(x)=1/4x(次方)- 1/2x(次方)+1的最大值和最小值
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f(x)=[(1/2)^x]^2-(1/2)^x+1
设t=1/2^x,-3<=x<=2,则有1/4<=t<=8
f(t)=t^2-t+1,(1/4<=t<=8)
=(t-1/2)^2+3/4
故当t=1/2时有最小值是:3/4
当t=8时有最大值是64-8+1=57
设t=1/2^x,-3<=x<=2,则有1/4<=t<=8
f(t)=t^2-t+1,(1/4<=t<=8)
=(t-1/2)^2+3/4
故当t=1/2时有最小值是:3/4
当t=8时有最大值是64-8+1=57
追问
谢谢
追答
x属于[-3,2],即是-3<=x<=2
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