Question

Помогите с алгеброй пожалуйста:

Answer 1

1)

$\displaystyle (0.4)^{2-x}=2.5^{1-\frac{2}{x}}\\\\ \frac{2}{5}^{2-x}= \frac{5}{2}^{\frac{x-2}{x} }\\\\ \frac{5}{2}^{x-2}= \frac{5}{2}^{ \frac{x-2}{x}}\\\\x-2= \frac{x-2}{x}\\\\ \frac{x(x-2)-(x-2)}{x}=0\\\\ \frac{(x-2)(x-1)}{x}=0\\\\x_1=2; x_2=2$

2)

$\displaystyle 3^{x+3}+3^{x+4}+3^{x+5}=13*9^x\\\\3^x*(3^3+3^4+3^5)=13*3^{2x}\\\\3^x*351=13*3^{2x}\\\\\frac{351}{13}= \frac{3^{2x}}{3^x}\\\\27=3^x\\\\3^3=3^x\\\\x=3$