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.
вправи поруч
