Question

Помогите 7 класс алгебра

Answer 1

▪13)

$\frac{1}{2} (x - 6) - 3 = \frac{1}{3} x \\ \frac{1}{2} x - \frac{1}{3} x = 3 + 3 \\ \frac{3 - 2}{6} x = 6 \\ \frac{1}{6} x = 6 \: \: \: \: \: | \times 6 \\ x = 36$

▪14)

$0.5(8x - 3) = - 4(2.5 - x) \\ 4x - 1.5 = - 10 + 4x \\ 4x - 4x = - 10 + 1.5$
х ∈ ∅


▪15)

$1.3x - 2 = 2.6x + 11 \\ 1.3x - 2.6x = 11 + 2 \\ - 1.3x = 13 \: \: \: \: \: | \div ( - 1.3) \\ x = - 10$

▪16)

$\frac{2}{3} (x + 9) - 2 = \frac{1}{6} x \\ \frac{2}{3} x - \frac{1}{6} x = 2 - 6 \\ \frac{4 - 1}{6} x = - 4 \\ \frac{3}{6} x = - 4 \\ \frac{1}{2} x = - 4 \: \: \: \: \: | \times 2 \\ x = - 8$

▪17)

$1.2(5 - 4x) = - 6(0.8x + 1) \\ 6 - 4.8x = - 4.8 x - 6 \\ - 4.8x + 4.8x = - 6 - 6 \\ 0 = - 12$
х ∈ ∅


▪18)
а)

$1.8y - 2 = 0.6y + 4 \\ 1.8y - 0.6y = 4 + 2 \\ 1.2y = 6 \: \: \: \: \: \: | \div 1.2 \\ y = 5$

б)
$1.2y - 1 = 0.4y + 3 \\ 1.2y - 0.4y = 3 + 1 \\ 0.9y = 4 \: \: \: \: \: \: | \div 0.9 \\ y = 4 \frac{4}{9}$