Question

subtract 5 a square + 7ab - 2 b square + 4 from 7a square - a b + 2 b square​

Answer 1

7a²-ab+2b² - 5a²-7ab+2b²

2a²-8ab+4b²

Answer 2

$(7 {a}^{2} - ab + 2 {b}^{2} ) - (5 {a}^{2} + 7ab - 2 {b}^{2} + 4) \\ 2 {a}^{2} - 8ab + 4 {b}^{2} - 4 \\ 2( {a}^{2} - 4ab + 2 {b}^{2} - 2)$

hope it helps.