Simplify: (3x^2 - 4xy + 7y^2) - (7x^2 - 6xy - 3y^2)

A. - 4x^2 - 10xy - 10y^2

B. - 4x^2 - 2xy + 10y^2

C. - 4x^2 - 10xy + 10y^2

D. - 4x^2 + 2xy + 10y^2

Distribute the Negative Sign: = 3 x2 - 4x y + 7 y2 + - 1 (7 x2 - 6x y - 3 y2) = 3 x2 + - 4x y + 7 y2 + - 1 (7 x2) + - 1 ( - 6x y) + - 1 ( - 3 y2) = 3 x2 + - 4x y + 7 y2 + - 7 x2 + 6x y + 3 y2

Combine Like Terms: = 3 x2 + - 4x y + 7 y2 + - 7 x2 + 6x y + 3 y2 = (3 x2 + - 7 x2) + ( - 4x y + 6x y) + (7 y2 + 3 y2) = - 4 x2 + 2x y + 10 y2

Answer: = - 4 x2 + 2x y + 10 y 2