Question

помогите. с номером 20

Answer 1

9^(7х+1)=81^(2х+4)
9^(7х+1)=9^(2*(2х+4))
7х+1=4х+8
7х-4х=8-1
3х=7
х=7/3

Answer 2

9⁷ˣ⁺¹=81²ˣ⁺⁴
9⁷ˣ⁺¹=9²ˣ⁺⁴ * 9²ˣ⁺⁴
9⁷ˣ⁺¹=9⁴ˣ⁺⁸
7х+1=4х+8
7х-4х=8-1
3х=7
х=7/3
ответ  Е