Вправа 367 алгебра Бевз гдз 7 клас

№ 367

1. a) (x – 1)(x – 3) = x² – 5
   x² – 3x – x + 3 – x² + 5 = 0
   –4x = –8
   x = 2;

б) (у + 2)(у – 5) – y(y – 1) = 2
y² – 5y + 2y – 10 – y² + y = 2
–2y = 12
y = 12 : (–2)
y = –6;

в) (2х + 1)(x – 5) = 2(х² + 11)
2x² – 10x + x – 5 = 2x² + 22
–9x = 27
x = –3;

г) 3z(z – 2) – 9 = (1 – z)(1 – 3z)
3z² – 6z – 9 = 1 – 3z – z + 3z²
–2z = 10
z = 10 : (–5)
z = –5.

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