Вправа 647 алгебра Бевз гдз 7 клас
№ 647
- a) (x + 1)2 + (x – 1)2 – 6 = ((x + 1 + x – 1) : 2)2
x2 + 2x + 1 + x2 – 2x + 1 – 6x = x2
x2 = 4
x1 = –2; х2 = 2;
б) (x + 1)2 + (x – 1)2 – 84 = (x + 1)(x – 1)
x2 + 2x + 1 + x2 – 2x + 1 – 84 = x2 – 1
x2 = 81
x1 = –9; х2 = 9.
вправи поруч
