Question

Calculati:

a) (x-7)(x+3)-(x+1)(x+2)+(5-x)(x-4)
b) (a-b)(a+3b)+(2a-b)(a+2b)-(a+b)(a-2b)
c) (2-x)(x+x²)-x²(3+x)+8+(x+2)(5+x²).

Answer 1

a)x²-4x-21-x²-3x-2+9x-20-x²=
  -x²+2x-43

b)a²+2ab-3b²+2a²+3ab-2b²-a²+ab+2b²=
   2a²+6ab-3b

c)2x+x²-x³-3x²-x³+8+5x+x³+10+2x²=
   -x³+7x+18