Question

$4^{2x-1} + 4^{2x-2}- 4^{2x-4} =316$
$3^{x+2} + 3^{x-8} geq 28$

Answer 1

4^(2x-1)+4^(2x-2)-4^(2x-4)=316
4^(2x-4)*(4^3+4^2-1)=316
4^(2x-4)*79=316
4^(2x-4)=4
2x-4=1
2x=5
x=5/2
3^(x+2)+3^(x-1)>=28
3^(x-1)(3^3+1)>=28
3^(x-1)28>=28
3^(x-1)>=1
x-1>=0
x>=1