1) 2x + 1. 2 = 0;

2x = -1. 2;

x = -1. 2 : 2;

x = -0. 6;

2) x + 1 = 0;

x = -1;

3) 0. 7x - 0. 21 = 0;

0. 7x = 0. 21;

x = 0. 21 : 0. 7;

x = 0. 3.

: x = -0. 6; x = -1; x = 0. 3 корни уравнения.