Question

Решить уравнение$2*9^{x}-3^{x+1} -2=0$

Answer 1

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

2*(3^x)^2 - 3*3^x - 2 = 0

y = 3^x  > 0

2y^2 - 3y - 2 = 0

D = 9 + 16 = 25

y12 = (3 +- 5)/4 = -1/2     2

y1 = -1/2  < 0 нет

y2 = 2

3^x = 2

x = log(3) 2