Question

Tìm x biết:

\(7^{x+2}\)+\(7^x\).2 = 51

Answer 1

=>7^x*49+7^x*2=51

=>7^x*51=51

=>7^x=1

=>x=0

Answer 2

\(7^{x+2}+7^x\cdot2=51\\ \Leftrightarrow7^x\cdot7^2+7^x\cdot2=51\\ \Leftrightarrow7^x\cdot51=51\\ \Leftrightarrow7^x=1\\ \Leftrightarrow x=0\)