Log_4(x+y)=2
log_4(x+y)=log_4(16)
x+y=16
x=16-y
log_3(x)+log_3(y)=2+log_3(7)
log_3(xy)=log_3(9*7)
xy=63
(16-y)y=63
16y-y^2=63
y^2-16y+63=0
D=16^2-4*63=4
y=(16+2)/2=9
y=(16-2)/2=7
x=16-9=7
x=16-7=9
Ответ: (7;9), (9;7)
log_4(x)-log_4(y)=0
log_4(x/y)=log_4(1)
x/y=1
x=y
x^2-5y^2+4=0
y^2-5y^2+4=0
4-4y^2=0/:4
1-y^2=0
y^2=1
y=1, y=-1
x=1, x=-1
Ответ: (1;1), (-1;-1)