Verified answer

1. Ответ: 37a²+17ab+9b²

[tex](7a + 2b)^{2} - (3a - b)(4a + 5b) = {49a}^{2} + 28ab + {4b}^{2} - {12a}^{2} - 15ab + 4ab + {5b}^{2} = {37a}^{2} + 17ab + {9b}^{2} [/tex]

2.

1) Ответ: m²n(6n-7m)(6n+7m)

[tex]36 {m}^{2} {n}^{3} - 49 {m}^{4} n = {m}^{2} n(36 {n}^{2} - 49 {m}^{2} ) = {m}^{2} n(6n - 7m)(6n + 7m)[/tex]

2) Ответ: 2(5+x)²

[tex]50 + 20x + {2x}^{2} = 2(25 + 10x + {x}^{2} ) = 2 {(5 + x)}^{2} [/tex]

3. Ответ: 1

[tex](3x - 2)(3x + 2) = 9x(x - 1) + 5 \\ {9x}^{2} - 4 = {9x}^{2} - 9x + 5 \\ {9x}^{2} - {9x}^{2} + 9x = 5 + 4 \\ 9x = 9 \\ x = 1[/tex]

4. Ответ: x=4 ; y=-5

[tex]\left \{ {{3x - y = 17 \: \:| \times 3} \atop {2x + 3y = - 7 \: \: \: \: \: \: \: \: }} \right. \\ \\ \left \{ {{9x - 3y = 51} \atop {2x + 3y = - 7}} \right. + \\ 11x = 44 \\ x = 4[/tex]

И вместо х поставим 4

[tex]2x + 3y = - 7 \\ 2 \times 4 + 3y = - 7 \\ 8 + 3y = - 7 \\ 3y = - 15 \\ y = - 5[/tex]