Question

x²+7x=2(x+7)

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Answer 1

х² + 7х = 2(х + 7)

х² + 7х = 2х + 14

х² + 7х - 2х - 14 = 0

х² + 5х - 14 = 0

D = b² - 4ac = 5² - 4 · 1 · (-14) = 25 + 56 = 81

√D = √81 = ±9

х = (-b±√D)2a

х₁ = (-5-9)/(2·1) = (-14)/2 = -7

х₂ = (-5+9)/(2·1) = 4/2 = 2

Ответ: -7; 2.