Question

х(х+40)=129
Ответ знаю)))

Answer 1

Ответ:

$x \times (x + 40) = 129 \\ x {}^{2} + 40x = 129 \\ {x}^{2} + 40x - 129 = 0 \\ x {}^{2} + 43x - 3x - 129 = 0 \\ x \times (x + 43) - 3 \times (x + 43) = 0 \\ (x + 43) \times (x - 3) = 0 \\ \: \: \: \: x + 43 = 0 \: \: \: \:x - 3 = 0 \\ x1 = \boxed{ - 43} \: \: \: \: \: x2 = \boxed{3}$