пусть f(x) = 2+3x
5^f(x) = 6,25 2^f(x)
5^f(x) / 2^f(x) = 6,25
5^f(x) / 2^f(x) = 25/4
(5/ 2)^f(x)= (5/2)^2
f(x) = 2
2+3x = 2
3x = 0
x = 0
Ответ: x = 0
sqrt(4/(19-3x))=0.4
4/(19-3x) = 0.4^2
4/(19-3x) = 0.16
4 = 0.16(19-3x)
4/0.16 = 19-3x
25 = 19 - 3x
6 = -3x
x = 6/-3
x = -2
Ответ: x = -2
log81 3^(2x+8) = 3
log3 3^(2x+8) = 3*4
2x + 8 = 3*4
2x + 8 = 12
2x = 4
x = 2
Ответ: 2
