Question

допоможіть будь ласка ​

Answer 1

Ответ:

7.

$(2x + 5)(3x - 7) = x(6x - 5) - 23 \\ 2x \times 3x + 2x \times ( - 7) + 5 \times 3x + 5 \times ( - 7) = x \times 6x + x \times ( - 5) - 23 \\ 6 {x}^{2} - 14x + 15x - 35 = 6 {x }^{2} - 5x - 23 \\ 6 {x}^{2} + x - 35 - 6 {x}^{2} + 5x + 23 = 0 \\ 6x - 12 = 0 \\ 6x = 12 \\ x = 12 \div 6 \\ x = 2$

8.

$1)12 {m}^{3} - 3 {m}^{4} - 18 {m}^{7} = 3 {m}^{3} (4 - m - 6 {m}^{4} )$

$2)xy + 7x - 7y - {x}^{2} = xy - {x}^{2} + 7x - 7y = - x( - y + x) + 7(x - y) = (7 - x)(x - y)$