Question

помогите 9^х-4·3^х-45

Answer 1

3^2x - 4*(3^x) - 45 = 0
3^x = z > 0
z^2 - 4z - 45 = 0
D = 16 + 4*1*45 = 196
z1 = (4 - 14)/2 = - 5 < 0 посторонний корень
z2 = (4 + 14)/2 = 9
3^x = 9
3^x = 3^2
x = 2