Question

tìm x:

3^x+2+3^x+1+3⁴=405

Answer 1

Tính M=4÷(7×31)+6÷(7×41)+9÷(10×41)+7÷(10×57)

Answer 2

\(3^{x+2}+3^{x+1}+3^4=405\)

\(3^{x+1}.3+3^{x+1}+81=405\)

\(3^{x+1}.\left(3+1\right)=405-81\)

\(3^{x+1}.4=324\)

\(3^{x+1}=81\)

\(3^{x+1}=3^4\)

\(x+1=4\)

\(x=3\)