5.85 Приведите подобные слагаемые: a) 3m + 2m + 4m; в) 0,9b - 1,3b + 0,7b; r) 1/12m - 1/4m - 1/3m; д) x - 0,2x - 0,7x; e) c - 0,8c - 1/5c - 1/2c;

a)

• \[ 3m + 2m + 4m = (3+2+4)m = 9m \]

в)

• \[ 0.9b - 1.3b + 0.7b = (0.9 - 1.3 + 0.7)b = 0.3b \]

r)

• \[ \frac{1}{12}m - \frac{1}{4}m - \frac{1}{3}m = \left( \frac{1}{12} - \frac{3}{12} - \frac{4}{12} \right) m = \frac{1-3-4}{12}m = \frac{-6}{12}m = -\frac{1}{2}m \]

д)

• \[ x - 0.2x - 0.7x = (1 - 0.2 - 0.7)x = 0.1x \]

e)

• \[ c - 0.8c - \frac{1}{5}c - \frac{1}{2}c = c - \frac{8}{10}c - \frac{1}{5}c - \frac{1}{2}c = c - \frac{4}{5}c - \frac{1}{5}c - \frac{1}{2}c = c \times \left( 1 - \frac{4}{5} - \frac{1}{5} - \frac{1}{2} \right) = c \times \left( 1 - 1 - \frac{1}{2} \right) = c \times \left( -\frac{1}{2} \right) = -\frac{1}{2}c \]

Ответ: a) 9m; в) 0.3b; r) -1/2m; д) 0.1x; e) -1/2c