Question

Subtract 5x2 - 4y2 + 6y -3 from 7x2 - 4xy + 8y2 - 3y+8​

Answer 1

$7 {x}^{2} - 4xy + 8 {y}^{2} - 3y + 8 - \\ (5 {x}^{2} - 4 {y}^{2} + 6y - 3) \\ \\ = 7 {x}^{2} - 4xy + 8 {y}^{2} - 3y + 8 - \\ 5 {x}^{2} + 4 {y}^{2} - 6y + 3 \\ \\ = 7 {x}^{2} - 5 {x}^{2} + 8 {y}^{2} + 4 {y}^{2} \\ - 3y - 6y - 4xy + 8 + 3 \\ \\ = 2 {x}^{2} + 12 {y}^{2} - 9y - 4xy + 11$