Question

Знайдіть корінь рівняння:
2. 20-3x=2х-45
1. 10х+7=8х-9
3. 2,7+1,9х=2х+1,5
4. 13/18х+13=7/12х+8

Answer 1

1.

$10x + 7 = 8x - 9 \\ 10x - 8x = - 9 - 7 \\ 2x = - 16 \\ x = - \frac{16}{2} = - 8$

2.

$20 - 3x = 2x - 45 \\ - 3x - 2x = - 45 - 20 \\ - 5x = - 65 \\ - x = - \frac{65}{5} \\ - x = - 13 \\ x = 13$

3.

$2.7 + 1.9x = 2x + 1.5 \\ 1.9x - 2x = 1.5 - 2.7 \\ - 0.1x = - 1.2 \\ - x = - \frac{1.2}{0.1} \\ - x = - 12 \\ x = 12$

4.

$\frac{13}{18} x + 13 = \frac{7}{12} x + 8 \\ \frac{13}{18} x - \frac{7}{12} x = 8 - 13 \\ \frac{26 - 21}{36} x = - 5 \\ \frac{5}{36} x = - 5 \\ x = - 5 \div \frac{5}{36} = - \frac{5 \times 36}{5} = - \frac{ 1 \times 36}{1} \\ x = - 36$