Вправи: 1291

1291. Знайдіть корінь рівняння:

1) 4(х – 5) = Зх;

4х – 20 = 3х;

4х – 3х = 20;

х = 20.

2) 6х = –2(х + 2);

6х = –2х – 4;

6х + 2х = –4;

8х = –4;

х = –0,5.

3) 3(2х – 5) = 5х – 3;

6х – 15 = 5х – 3;

6х – 5х = 15 – 3;

х = 12.

4) –(Зх + 1) = 2х – 9;

–3х – 1 = 2х – 9;

–3х – 2х = 1 – 9;

–5х = –8;

х = 1,6.

5) 7(х + 2) = 3(х – 4);

7х + 14 = 3х – 12;

7х – 3х = –12 – 14;

4х = –26;

х = –6,5.

6) 4(х – 1) = –5(х – 10);

4х – 4 = –5х + 50;

4х + 5х = 50 + 4;

9х = 54;

х = 6.