Раскройте скобки и приведите подобные слагаемые: a) -(a + 2,1b) + (3,8a - 1,9b); б) 3 1/3 * (0,3y - 0,6) - 1 1/4 * (0,8 - 1,6y); а) (1,2a + 2,4b) - (4,3a + b); б) -1 3/7 * (1,4 - 0,7y) + 0,6 * (1 2/3 - 5y).

a) -(a + 2.1b) + (3.8a - 1.9b) = -a - 2.1b + 3.8a - 1.9b = -a + 3.8a - 2.1b - 1.9b = 2.8a - 4b б) 3 1/3 * (0.3y - 0.6) - 1 1/4 * (0.8 - 1.6y) = 10/3 * (3/10y - 6/10) - 5/4 * (8/10 - 16/10y) = 10/3 * 3/10y - 10/3 * 6/10 - 5/4 * 8/10 + 5/4 * 16/10y = y - 2 - 1 + 2y = 3y - 3 а) (1.2a + 2.4b) - (4.3a + b) = 1.2a + 2.4b - 4.3a - b = 1.2a - 4.3a + 2.4b - b = -3.1a + 1.4b б) -1 3/7 * (1.4 - 0.7y) + 0.6 * (1 2/3 - 5y) = -10/7 * (14/10 - 7/10y) + 6/10 * (5/3 - 5y) = -10/7 * 14/10 + 10/7 * 7/10y + 6/10 * 5/3 - 6/10 * 5y = -2 + y + 1 - 3y = -1 - 2y