(8/7)^x×(7/8)^-y=64/49
(21)^-8=21^xy
5^x>5^y
(8/7)^x×(8/7)^y=(8/7)^2
-8=xy
x>y
x+y=2
xy = -8
x>y
x = 2 - y
y(2 - y) = -8
2y - y^2 = - 8
y^2 - 2y - 8 = 0
D = 4 + 32 = 36
y12 = (2 +- 6)/2 = -2 4
1. y1 = -2
x1 = 2 - (-2) = 4
4 > -2 да
2. y2 = 4
x2 = 2 - 4 = -2
-2 < 4 нет
ответ (4, -2)
