设不等式2(log1⼀2^x)^2+9(log1⼀2^x)+9≤0的解集为M

求当x属于m时f(x)=(log2^x/2)(log2^x/8)的最大、最小值
2025-01-05 17:09:07
推荐回答(1个)
回答(1):

(2(log1/2x) 3)((log1/2x) 3)<=0

-3<=log1/2x<=-3/2

换底公式 log1/2x=log(2)x/log2(1/2)=-log(2)x

∴3/2<=log(2)x<=3
令y=log(2)x 3/2<=y<=3
f(x)=(y-1)(y-3)=y²-4y 3=(y-2)²-1
y=2时,有最小值-1
y=3时,有最大值0