Mohon dibantuu yaa kaak atau baang:):)

2/x + 2/y = 7
2 × (1/x + 1/y) = 7
1/x + 1/y = 7/2
y/xy + x/xy = 7/2
(y+x)/xy = 7/2

3,5/x - 3,5/y = 6
3,5 × (1/x - 1/y) = 6
1/x - 1/y = 6/3,5
y/xy - x/xy = 60/35
(y-x)/xy = 12/7

1/x²-1/y² =
y²/(x²y²) - x²/(x²y²) =
(y²-x²)/(x²y²) =
(y+x)(y-x)/(xy)² =
(y+x)/xy × (y-x)/xy =
7/2 × 12/7 = 6

1/x²-1/y² = 6
(1/x²-1/y²)² = 6² = 36
Jadi, (1/x²-1/y²)² = 36 (D)