(g-y)^2-g^2-y^2+4d-18d-7(1-2d)=3

Question

(g-y)^2-g^2-y^2+4d-18d-7(1-2d)=3

Answer 1

(g-y)²-g²-y²+4d-18d-7(1-2d)=3
g²-2gy+y²-g²-y²+4d-18d-7+14d=3
g²-2gy+y²-g²-y²+4d-18d+14d=3+7
-2gy=10