Réponses

2014-10-07T19:40:27+02:00
9x² - (2x-1)²
= 9x² - 4x² - 1
= 5x² - 1

(1-x)(3x-2) - 2x (1-x)
= 1*3 +  1*(-2) + (-x)*3 + (-x)*2 - 2x*1 -2x*x
= 3 -2 -3x - 2x - 2x - 2x²
= 1 - 7x - 2x²

(4x + 7)² + 4x + 7
=16x² + 49 + 4x + 7
16x² + 56 + 4x