№2 Упрости: a) a + (1,1a – 10) – (12 + 1,2a); б) (1 – 0,9y) – (2,2y – 4) – 5; в) (6,2x – 8) – 5x – (4 – 9,1x); г) 5,3b – (6,4b + a) – (1,8a – 0,6b).

Решение:

Раскроем скобки и приведем подобные слагаемые.

а) \( a + (1.1a - 10) - (12 + 1.2a) = a + 1.1a - 10 - 12 - 1.2a = (a + 1.1a - 1.2a) + (-10 - 12) = 0.9a - 22 \)

б) \( (1 - 0.9y) - (2.2y - 4) - 5 = 1 - 0.9y - 2.2y + 4 - 5 = (-0.9y - 2.2y) + (1 + 4 - 5) = -3.1y + 0 \) = \( -3.1y \)

в) \( (6.2x - 8) - 5x - (4 - 9.1x) = 6.2x - 8 - 5x - 4 + 9.1x = (6.2x - 5x + 9.1x) + (-8 - 4) = 10.3x - 12 \)

г) \( 5.3b - (6.4b + a) - (1.8a - 0.6b) = 5.3b - 6.4b - a - 1.8a + 0.6b = (5.3b - 6.4b + 0.6b) + (-a - 1.8a) = -0.5b - 2.8a \)

Ответ: а) 0.9a - 22; б) -3.1y; в) 10.3x - 12; г) -2.8a - 0.5b