Вправи: 67

67. Виконайте дії:

1) a+bc-7 + a7-c = a+bc-7 + a-(c-7) = a+bc-7 – ac-7 = a+b-ac-7 = bc-7;

2) 5mm-n + 5nn-m = 5mm-n + 5n-(m-n) = 5mm-n – 5nm-n = 5m-5nm-n = 5(m-n)m-n = 5;

3) 2x-4yx-3y – 4x-14y3y-x = 2x-4yx-3y – 4x-14y-(x-3y) = 2x-4yx-3y + 4x-14yx-3y = 2x-4y+ (4x-14y)x-3y = 2x-4y+4x-14yx-3y = 6x-18yx-3y = 6(x-3y)x-3y = 61 = 6;

4) 81b29b-a + a2a-9b = 81b29b-a + a2-(9b-a) = 81b29b-a – a29b-a = 81b2- a29b-a = 9b-a(9b+a)9b-a = 9b+a2 = 9b + a;

5) t23t-6 + 46-3t = t23t-6 + 4-(3t-6) = t23t-6 – 43t-6 – 43t-6 = t2- 43t-6 = t-2(t+2)3(t-2) = t+22;

6) y2y-1 – 1-2y1-y = y2y-1 – 1-2y-(y-1) = y2y-1 + 1-2yy-1 = y2+ 1-2yy-1 = (y-1)2y-1 = y-11 = y – 1.