Решите уравнение 9^ (х) + 2*3^ (х+1) - 7=0

9 ^ x + 2 * 3 ^ (x + 1) - 7 = 0

3 ^ 2x + 2 * 3 ^ (x + 1) - 7 = 0

3 ^ x = a; a > 0

a² + 6a - 7 = 0

D = 36 + 28 = 64; √ D = 8

a1 = ( - 6 + 8) : 2 = 1

a2 = ( - 6 - 8) : 2 = - 7 (< 0)

3 ^ x = 1

3 ^ x = 3 ^ 0

x = 0