Реши уравнения: а)4(х-3)-16=5(х-5) б)15(2х-5)+2х=5(5х-15)-7

а) 4 * (х – 3) – 16 = 5 * (х – 5);

4 * х – 4 * 3 – 16 = 5 * х – 5 * 5;

4х – 12 – 16 = 5х – 25;

4х – 5х = - 25 + 12 + 16;

-х = 3;

х = -3.

Проверка:

4 * (-3 – 3) – 16 = 5 * (-3 – 5);

4 * (-6) – 16= 5 * (-8);

-24 – 16 = - 40;

-40 = -40.

б) 15 * (2х – 5) + 2х = 5 * (5х – 15) – 7;

15 * 2х – 15 * 5 + 2х = 5 * 5х – 5 * 15 – 7;

30х – 75 + 2х = 25х – 75 – 7;

30х + 2х – 25х = -75 – 7 + 75;

7х = -7;

х = -7 : 7;

х = -1.

Проверка:

15 * (2 * (-1) – 5) + 2 * (-1) = 5 * (5 * (-1) – 15) – 7;

15 * (-2 – 5) – 2= 5 * (-5 – 15) – 7;

15 * (-7) – 2 = 5 * (-20) – 7;

-105 – 2 = -100 – 7;

-107 = -107.