2. Упрости выражение: а) 4m – 6m – 3m + 7 + m; б) –8(k – 3) + 4(k – 2) – 2(3k + 1); в) 5/9 · (3,6a – 3 3/5b) – 3,5 · (4/7a – 0,2b).

Решение:

1. а) 4m – 6m – 3m + 7 + m = (4 – 6 – 3 + 1)m + 7 = –4m + 7
2. б) –8(k – 3) + 4(k – 2) – 2(3k + 1) = –8k + 24 + 4k – 8 – 6k – 2 = (–8 + 4 – 6)k + (24 – 8 – 2) = –10k + 14
3. в) 5/9 · (3,6a – 3 3/5b) – 3,5 · (4/7a – 0,2b)
• = 5/9 · (36/10a – 18/5b) – 35/10 · (4/7a – 2/10b)
• = 5/9 · (18/5a – 18/5b) – 7/2 · (4/7a – 1/5b)
• = (5/9 · 18/5a) – (5/9 · 18/5b) – (7/2 · 4/7a) + (7/2 · 1/5b)
• = 2a – 2b – 2a + 7/10b
• = (2a – 2a) + (–2b + 7/10b)
• = 0a + (–20/10b + 7/10b) = –13/10b = –1,3b

Ответ: а) –4m + 7; б) –10k + 14; в) –1,3b