Question

1)2lg5 + 1/2lg16
2)log4(13-x) = 2
3)log0.2(x^+4x)=-1
Решите. по фасту плиз

Answer 1

1) 2lg5 + 1/2lg16 = lg5^2 + lg16^(1/2) = lg25 + lg4 = lg100 = lg10^2 = 2
2) log_4_(13 - x) = 2
log_4_(13 - x) = log_4_16
13 - x = 16
x = -3
3) log_0.2_(x^2 + 4x) = -1
log_0.2_(x^2 + 4x) = log_0.2_5
x^2 + 4x = 5
x^2 + 4x - 5 = 0
D=16+20=36
X1=-5
X2=1