1. -2$\frac{3}{4}$ + $-1\frac{1}{2}$ - (-5,6) : 0,8 + $\frac{3}{7}$ 2. $\frac{2}{3}$ : $\frac{5}{12}$ - $\frac{8}{15}$ + 3$\frac{1}{5}$ 3. (16m^2 - 8mn + n^2)(4m^2 - n^2) - 256m^4 + n^4 при m = 1, n = -2 4. 0,4(3x - 5) - 0,2(6x - 3) = 1,2 - 0,5x

Question

$Фото задания: 1. -2$\frac{3}{4}$ + $-1\frac{1}{2}$ - (-5,6) : 0,8 + $\frac{3}{7}$ 2. $\frac{2}{3}$ : $\frac{5}{12}$ -…$ Фото задания

Accepted Answer

$-2\frac{3}{4} + ( -1\frac{1}{2} ) - (-5,6) : 0,8 + \frac{3}{7} = -2\frac{3}{4} - 1\frac{1}{2} + 5,6 : 0,8 + \frac{3}{7} = -2\frac{3}{4} - 1\frac{2}{4} + 7 + \frac{3}{7} = -3\frac{5}{4} + 7 + \frac{3}{7} = -4\frac{1}{4} + 7 + \frac{3}{7} = 2\frac{3}{4} + \frac{3}{7} = \frac{21+12}{28} = \frac{33}{28} = 1\frac{5}{28}$
$\frac{2}{3} : \frac{5}{12} - \frac{8}{15} + 3\frac{1}{5} = \frac{2}{3} \times \frac{12}{5} - \frac{8}{15} + \frac{16}{5} = \frac{8}{5} - \frac{8}{15} + \frac{16}{5} = \frac{24-8+48}{15} = \frac{64}{15} = 4\frac{4}{15}$
$(16m^2 - 8mn + n^2)(4m^2 - n^2) - 256m^4 + n^4 = (4m-n)^2 (2m-n)(2m+n) - 256m^4 + n^4$
При $ m = 1, n = -2 $: $(16 - 8(1)(-2) + (-2)^2)(4(1)^2 - (-2)^2) - 256(1)^4 + (-2)^4 = (16 + 16 + 4)(4 - 4) - 256 + 16 = (36)(0) - 256 + 16 = -240$
$0,4(3x - 5) - 0,2(6x - 3) = 1,2 - 0,5x$
$1,2x - 2 - 1,2x + 0,6 = 1,2 - 0,5x$
$-1,4 = 1,2 - 0,5x$
$0,5x = 1,2 + 1,4$
$0,5x = 2,6$
$x = \frac{2,6}{0,5} = 5,2$

Ответ: 1. $1\frac{5}{28}$ 2. $4\frac{4}{15}$ 3. -240 4. 5,2

1. -2\(\frac{3}{4}\) + \(-1\frac{1}{2}\) - (-5,6) : 0,8 + \(\frac{3}{7}\) 2. \(\frac{2}{3}\) : \(\frac{5}{12}\) - \(\frac{8}{15}\) + 3\(\frac{1}{5}\) 3. (16m^2 - 8mn + n^2)(4m^2 - n^2) - 256m^4 + n^4 при m = 1, n = -2 4. 0,4(3x - 5) - 0,2(6x - 3) = 1,2 - 0,5x