Question

Помогите, пожалуйста. Очень срочно

Даю 45 баллов!

1) 7^(1-5x)= 1/49.

2)5^(x+1)-2*5(x-1)=115.

3)6*5^(2x)+5^(x)-7=0.

4)5*3^(x)-2^(x+3)=3^(x)+2^(x).

Answer 1

Ответ:

$1) {7}^{1 - 5x} = {7}^{ - 2} \\ 1 - 5x = - 2 \\ - 5 x = - 3 \\ x = \frac{3}{5}$

$2) {5}^{x - 1} ( {5}^{2} - 2) = 115 \\ {5}^{x - 1} \times 23 = 115 \\ {5}^{x - 1} = 5 \\ x - 1 = 1 \\ x = 2$

$3) {5}^{x} = t \\ 6 {t}^{2} + t - 7 = 0 \\ t1 =1 \\ t2 = \frac{ - 7}{6} \\ {5}^{x} = 1 \\ x = 0 \\ {5}^{x} = - \frac{7}{6} \\ net \: korney$

Ответ: 0

$4)5 \times {3}^{x} - {3}^{x} = {2}^{ x + 3} + {2}^{x } \\ {3}^{x} (5 - 1) = {2}^{x} ( {2}^{3} + 1) \\ {3}^{x} \times 4 = {2}^{x} \times 9 \\ ( { \frac{3}{2} })^{x} = \frac{9}{4} \\ x = 2$