Question

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Решить уравнение

(2x − 5)(x + 3) = 7x + 21

Answer 1

$2 {x}^{2} + 6x - 5x - 15 = 7x + 21 \\ 2 {x}^{2} - 6x - 36 = 0 \\ d = 36 + 288 = 324 \\ x1 = \frac{6 + 18}{4} = 6 \\ x2 = \frac{6 - 18}{4} = - 3$