Răspuns:
x²-3x+x-3-(x²+6x-7x-42)=
=x²-2x-3-x²-6x+7x+42=
=x+39
= 39-x
Explicație pas cu pas:
a) (x + 1)(x-3) - (x-7)(x+6) = ?
(x + 1)(x-3) = x²-3x+x-3 = x²-2x-3
(x-7)(x+6) = x²+6x-7x-42 = x²-x-42
(x + 1)(x-3) - (x-7)(x+6) = (x²-2x-3) - ( x²-x-42) =
= x²-2x-3 -x²+x+42 = -x + 39 = 39-x
