Question

281. решите уравнение -5,4-(х-7,2)=1,9 304. решите уравнение а) 0,3(5х-7)=3(0,2х+3,2) б)4(1,2х+3,7)-2,8=5,2х в) (4/1/6у+11/1/4)4/15=2/3у+5/2/3 ) заранее

Answer 1

▪281.

$- 5.4 - (x - 7.2) = 1.9 \\ - (x - 7.2) = 1.9 + 5.4 \\ - x + 7.2 = 7.3 \\ - x = 7.3 - 7.2 \\ - x = 0.1 \\ x = - 0.1$

▪304.

a)

$0.3(5x - 7) = 3(0.2x + 3.2) \\ 1.5x - 2.1 = 0.6x + 9.6 \\ 1.5x - 0.6x = 9.6 + 2.1 \\ 0.9x = 11.7 \: \: \: \: \: | \div 0.9 \\ x = 13$

б)

$4(1.2x + 3.7) - 2.8 = 5.2x \\ 4.8x + 14.8 - 2.8 = 5.2x \\ 12 = 5.2x - 4.8x \\ 0.4x = 12 \: \: \: \: \: | \div 0.4 \\ x = 30$

в)

$(4 \frac{1}{6} y + 11 \frac{1}{4} ) \times \frac{4}{15} = \frac{2}{3} y + 5 \frac{2}{3} \\ \frac{25 \times 4}{6 \times 15} y + \frac{45 \times 4}{4 \times 15} - \frac{2}{3} y = 5 \frac{2}{3} \\ \frac{5 \times 2}{3 \times 3} y + \frac{3 \times 1}{1 \times 1} - \frac{2}{3} y = 5 \frac{2}{3} \\ \frac{10}{9} y - \frac{2}{3} y = 5 \frac{2}{3} - 3 \\ 1 \frac{1}{9} y - \frac{6}{9} y = 2 \frac{2}{3} \\ 1 - \frac{5}{9} y = 2 \frac{2}{3} \\ \frac{4}{9} y = \frac{8}{3} \\ y = \frac{8}{3} \div \frac{4}{9} = \frac{8 \times 9}{3 \times 4} = \frac{2 \times 3}{1} \\ y = 6$