4^x-17×2^(x-1)+4≤0
(2^x)^2-(17/2)×2^x+4≤0
2×(2^x)^2-17×2^x+8≤0
(2^x-8)(2×2^x-1)≤0
1/2≤2^x≤8
-1≤x≤3