Question

помогите пожалуйста​

Answer 1

Ответ:

1)

а)

$(5x {}^{2} + 8x - 7) - (2x {}^{2} - 12) = 5x {}^{2} + 8x - 7 - 2x {}^{2} + 2x + 12 = 3x {}^{2} + 10x + 5$

б)

$(14ab - 9a {}^{2} - 3b {}^{2} ) - (3a {}^{2} + 5ab - 4b {}^{2} ) = 14ab - 9a {}^{2} - 3b {}^{2} - 5ab + 4b {}^{2} = 9ab - 12a {}^{2} + b {}^{2}$

2)

$5 - (3 + 4x - 2x {}^{2} ) = 2x {}^{2} - 3x + 8 \\ 5 - 3 - 4x + 2x {}^{2} = 2x {}^{2} - 3x + 8 \\ 5 - 3 - 4x = - 3x + 8 \\ 2 - 4x = - 3 + 8 \\ - 4x + 3x = 8 - 2 \\ - x = 6 \\ x = - 6$