Вправа 498 алгебра Бевз гдз 7 клас

№ 498

а) (x – 5)² – 2x(x + 3) + (x – 6)² = 5
x² – 10x + 25 – 2x² – 6x + x² – 12x + 36 = 5
–28x = 5 – 61
–28x = –56
x = –56 : (–28)
x = 2;
б) (3z + 1)² – 8z(z + 1) = (z – 3)²
9z² + 6z + 1 – 8z² – 8z = z² – 6z + 9
6z – 8z + 6z = 9 – 1
4z = 8
z = 2.