Exercice 1
A. -2n^2 * (-9) = 2n^2 * 9 (on enlève les -) = (2*9)n^2 =18n^2
B. (-9x6)*y^2 = -54y^2
C. -2t*5 = -10t
D. -7x^2*(-2) = 14x^2
E.7s-4s = (7-4)s = 3s
F. 3*4s^2 = 12s^2
Exercice 2
A = 4x * -4x + 4x * (-10) = -16x^2 - 40x
B = (-9x+7)*10 = -9x*10+7*10 = -90x+70
C = 5x(-6x+8) = 5x*(-6x)+5x*8 = -30x^2+40x
D = (3x-5)(6x+8) = 3x*6x+3x*8-5*6x-5*8 = 18x^2+24x-30x-40 = 18x^2-6x-40
E = (-6x+6)(-8x+6) = -6x*(-8x)-6x*6-6*8x+6*6 = 48x^2-36x-48x+36 = 48x^2-84x+36
F = (10x-7)(6x+2) = 60x^2+20x-42x-14 = 60x^2-22x-14
Exercice 3
A = 2(x+1)+(3x-4) = 2x+2+3x-4 = 5x-2 (rassembler les termes de même nature, 2x+3x et +2-4)
B = 5(3x-2)-(x+7)=15x-10-x-7=14x-17
C = (3x+4)(2x+1)+(x+4)(7x-6)= 6x^2+3x+8x+4+7x^2-6x+28x-24 = 13x^2+33-20
D = x^2+8x+4x+32-(5x^2-30x+3x-18)= x^2+8x+4x+32-(5x^2-27x-18) = x^2+8x+4x+32-5x^2+27x+18 (car s'il y a un signe moins devant la parenthèse, enlever la parenthèse et changer tous les signes + en - et les signes - en +) = -4x^2+39x+50
a^n = [tex]a^n[/tex]
