Par exemple :
A = (2x+5)(-3x-1)-5(2-x)
= 2x*(-3x)+2x*(-1)+5*(-3x)+5*(-1)-5*2-5*(-x)
= -6x²-2x-15x-5 - 10 + 5x
= -6x²-12x-15
B = 2(-3x+5)+(-3x+7)(2x-9)
= 2*(-3x)+2*5+(-3x)*2x+(-3x)*(-9)+7*2x+7*(-9)
= -6x+10-6x²+27x+14x-63
= -6x²+35x-53
C = 2t(3-4t)-(5-a)+(9t+2)(3t-3)
= 2t*3+2t*(-4t)-5+a+9t*3t+9t*(-3)+2*3t+2*(-3)
= 6t-8t²-5+a+27t²-27t+6t-6
= 19t²-15t+a-11
