Вправи: 485

485. Розв’яжи рівняння.

a) (x – 2)² = x(x – 3);

x² – 4x + 4 = x² – 3x;

–4x + 3x = –4;

–x = –4|: (–1);

x = 4.

б) (3y + 5)² = 9y² + 55;

9y² + 30y + 25 = 9y² + 55;

30y = 55 – 25;

30y = 30|: 30;

y = 1.

в) (c – 7)² – 2(c – 2) = c² + 21;

c² – 14c + 49 – 2c + 4 = c² + 21;

–16c = 21 – 53;

–16c = –32|: (–16);

c = 2.

г) (6 – x)² = (x + 8)(x – 4) + 4;

36 – 12x + x² = x² – 4x + 8x – 32 + 4;

–12x – 4x = –32 – 36 + 4;

–16x = –64|: (–16);

x = 4.