12a(a + 4) - 3a(4a - 1) - 50(a + 2) - a = 12a² +48a - 12a² + 3a - 50a - 100 - a =
= - 100
12a(a+4)-3a(4a-1)-50(a+2)-a = 12a²+48a-12a²+3a-50a-100-a = (12a²-12a²)+(48a+3a-50a-a)-100 = -100.
12a(a + 4) - 3a(4a - 1) - 50(a + 2) - a = 12a² +48a - 12a² + 3a - 50a - 100 - a =
= - 100
12a(a+4)-3a(4a-1)-50(a+2)-a = 12a²+48a-12a²+3a-50a-100-a = (12a²-12a²)+(48a+3a-50a-a)-100 = -100.