Question

Пожалуйста, помогите решить уравнение!
1) х+12=3х;
2) х/2+х/3=4;
3) 4-х/7=х/9.

Answer 1

$x + 12 = 3x \\ x - 3x = - 12 \\ - 2x = - 12 \\ x = 6$

$x \div 2 + x \div 3 = 4 \\ \frac{1}{2} x + \frac{1}{3} x = 4 \\ \frac{3}{6} x + \frac{2}{6} x = 4 \\ \frac{5}{6} x = 4 \\ x = 4 \div \frac{5}{6} \\ x = \frac{4 \times 6}{1 \times 5} \\ x = \frac{24}{5} \\ x = 4.8$

$4 - x \div 7 = x \div 9 \\ 4 = \frac{x}{7} + \frac{x}{9} \\ 4 = \frac{9x}{63} + \frac{7x}{63} \\ 4 = \frac{16x}{63} \\ 4 = 16x \div 63 \\ 63 \times 4 = 16x \\ 252 = 16x \\ x = 252 \div 16 \\ x = 15.75$