Вправи: 279

279. Розв’яжи рівняння.

a) (4x – 5) – (7x + 8) = 2;

4x – 5 – 7x – 8 = 2;

–3x = 5 + 8 + 2;

–3x = 15|: (–3);

x = –5.

б) 9z + 17 – (4z – 6) = 38;

9z + 17 – 4z + 6 = 38;

5z = –17 – 6 + 38;

5z = 15|: 5;

z = 3.

в) (5x + x³ – 7) – (2x³ + 3x) = –(1 + x³);

5x + x³ – 7 – 2x³ – 3x = –1 – x³;

–x³ + 2x= –x³ + 7 – 1;

2x = 6|: 2;

x = 3.

г) 19 – (3x² – 2x) – (6x – x²) = 7 – 2x²;

19 – 3x² + 2x – 6x + x² = 7 – 2x²;

–2x² – 4x = –2x² – 19 + 7;

–4x = –12|: (–4);

x = 3.