Вправа 499 алгебра Бевз гдз 7 клас

№ 499

а) (2x + 5)² + 2x(x – 6,5) = (2x – 3)(3x + 1)
4x² + 20x + 25 + 2x² – 13x = 6x² + 2x – 9x – 3
20x – 13x – 2x + 9x = –3 – 25
14x = –28
x = –28 : 14
x = –2;

б) (3x + 8)² + 11(x² + 2) – 2(3x + 4)² = 2(x – 3)²
9x² + 48x + 64 + 11x² + 22 – 18x² – 48x – 32 = 2x² – 12x + 18
12x = –36
x = –36 : 12
x = –3;

в) (6x – 5)² – 4(2x + 1)² = 10(2x – 1)(x – 3)
36x² – 60x + 25 – 16x² – 16x – 4 = 20x² – 70x + 30
–60x – 16x + 70x = 30 – 25 + 4
–6x = 9
x = 9 : (–6)
x = –1,5.