№8. Упростите выражение и приведите подобные слагаемые: a)(3,2x+10y)·5-12·(4x-0,5y); б)3/4·(2,8a-1,2c)+2/7·(1,4a+2,1c); в)0,2·(2,1x-2,3y)-0,4·(3,1y+1,9x); г)4/15·(1 2/3m-4,5)-1 1/2·(8/27m+5,4)

№8. Упрощение выражений

1. а) (3.2x + 10y) \(\cdot\) 5 - 12 \(\cdot\) (4x - 0.5y) = 16x + 50y - 48x + 6y = -32x + 56y
2. б) \(\frac{3}{4}\) \(\cdot\) (2.8a - 1.2c) + \(\frac{2}{7}\) \(\cdot\) (1.4a + 2.1c) = 2.1a - 0.9c + 0.4a + 0.6c = 2.5a - 0.3c
3. в) 0.2 \(\cdot\) (2.1x - 2.3y) - 0.4 \(\cdot\) (3.1y + 1.9x) = 0.42x - 0.46y - 1.24y - 0.76x = -0.34x - 1.7y
4. г) \(\frac{4}{15}\) \(\cdot\) (1 \(\frac{2}{3}\)m - 4.5) - 1 \(\frac{1}{2}\) \(\cdot\) (\(\frac{8}{27}\)m + 5.4) = \(\frac{4}{15}\) \(\cdot\) (\(\frac{5}{3}\)m - 4.5) - \(\frac{3}{2}\) \(\cdot\) (\(\frac{8}{27}\)m + 5.4) = \(\frac{4}{9}\)m - 1.2 - \(\frac{4}{9}\)m - 8.1 = -9.3