Question

please help it's very urgent ​

Answer 1

4. 5x²-4

5. 5ab + 6a² + 2b²

Answer 2

Answer:

$4. \: \: \: \: \: \: \:(2 {x}^{2} + 5x - 7) - (7 {x}^{2} - 5x + 3) \\ = 2 {x}^{2} + 5x - 7- 7 {x}^{2} - (- 5x ) - ( + 3)\\ = 2 {x}^{2} + 5x - 7- 7 {x}^{2} + 5x - 3\\2 {x}^{2} - 7 {x}^{2} + 5x + 5x - 7 - 3 \\ = - 5 {x}^{2} + 10x - 10$

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$5.(2ab + 7 {a}^{2} + 8 {b}^{2} ) - (10 {b}^{2} + 7ab + {a}^{2} ) \\ = 2ab + 7 {a}^{2} + 8 {b}^{2} - 10 {b}^{2} - 7ab - {a}^{2} \\ = 2ab - 7ab + 7 {a}^{2} - {a}^{2} + 8 {b}^{2} - 10 {b}^{2} \\ = - 5ab + 6 {a}^{2} - 2 {b}^{2}$