Question

0.3^(2+4+6+...+2x)>0.3^72

Answer 1

$0.3^{2+4+6+...+2x}>0.3^{72}\\ 0.3^{\frac{2*2+2(x-1)}{2}*x}>0.3^{72}\\ (1+x)x>72\\ x+x^2>72\\ x^2+x-72>0\\ (x+9)(x-8)>0\\ ---------------->x\\ + \ \ \ (-9) \ \ \ \ \ \ \ - \ \ \ \ \ \ \ \ \ \ \ \ \ 8 \ +\\ (-oo;-9) \ U \ (8;+oo)$