упростите выражение, приводя подобные слагаемые 1) a+4b-a-7b 2) -2x+3.7+2x-5 3) a-4/5a-1/7a

Приведем подобные слагаемые.

1) a + 4b - a - 7b = a (1 - 1) + b (4 - 7) = a * 0 - 3b = - 3b.

2) - 2x + 3.7 + 2x - 5 = x (2 - 2) - 1.3 = x * 0 - 1.3 = - 1.3.

3) a - 4/5a - 1/7a = a (1 - 4/5 - 1/7) = a (35/35 - (4 * 7)/35 - (1 * 5)/35) =

a (35/35 - 28/35 - 5/35) = a (35 - 28 - 5)/35 = 2/35a.

4) 0.2d - 2/3 - 2d + 5/9 = d (0.2 - 2) + 5/9 - (2 * 3)/9 = - 1.8d + 5/9 - 6/9 = - 1.8d +

(5 - 6)/9 = -  1.8d - 1/9.

5) y - 3.2 + 2y - 4.6 - 5y = y (1 + 2 - 5) - 7.8 = - 2y - 7.8.

6) - z + 2.3x + 0.11z + 8.9x = z (0.11 - 1) + x (2.3 + 8.9) = - 0.89z + 11.2x.

7) - c + 2/3b - 2/7c - 4/9b = - c (1 + 2/7) + b (2/3 - 4/9) = - c (7/7 + 2/7) + b ((2 * 3)/9 - 4/9) = - c (7 + 2)/7 + b (6/9 - 4/9) = - 9/7c + b (6 - 4)/9 = - 1 2/7c + 2/9b.

8) m - 0.8m - 1/5m - 1/2m = m (1 - 8/10 - 1/5 - 1/2) = m (10/10 - 8/10 - 2/10 - 5/10) =

m (10 - 8 - 2 - 5)/10 = - 5/10m = - 1/2m.