Question

3^x-1-3^x-2=18 и 9^x-1-3^x-2=30 ПОМОГИТЕ РЕШИТЬ

Answer 1

1)  3^(x - 1) - 3^(x - 2) = 18
(1/3)*(3^x) - (1/9)*(3^x) = 18
(2/9)*(3^x) = 18
 3^x = 81
3^x = 3^4
x = 4
2) 9^(x - 1) - 3^(x - 2) = 30
(1/9)*3^(2x) - (1/9)*(3^x)  - 30 = 0
3^(2x) - (3^x) - 270 = 0
D = 1 + 4*1*270 = 1081
3^x = (1 - √1081)/2 < 0
3^x = (1 + √1081)/2
x = log₃ (1 + √1081)/2