EXERCICE 9
A = 6x² + 9x +3 x²- 6 - 2x
=6x²+3x² + 9x-2x -6
=9x² +7x -6
B=11x +7x -6x² -2x -4x²
= -6x²-4x² +11x+7x-2x
=-10x² +17x
=x (-10x +17)
C=8x +5 -2x² -7x -15+ 8x²
=-2x² +8x² +8x-7x +5-15
=6x² +x -10
D=6x² +3x +12x -9 -10x² +x -4
=6x² -10x² +3x +12x +x -9 -4
=-4x² +16x -13
EXERCICE 11
a) (2+x)(15-y) = 30 -2y +15x -xy = -xy +15x -2y +30
b) (7+y)(y-4) = 7y -28 +y² -4y = y² +7y -4y -28 = y² +3y -28
c) (z-25)(x+z) = zx +z² -25x +25z = z² +25z -25x +zx
d) (t-3)(t-13) = t² -13t -3t +39 = t² -16t +39
EXERCICE 15
i) (x+5)(10+7x) = 10x +7x² +50 +35x = 7x² +35x +10x +50 = 7x² +45x +50
j) (4x +2)(x-12) = 4x² -48x +2x -24 = 4x² -46x -24 = 2(2x² -23x +12)
k) (5-9x)(2x +8) = 10x +40 -18x² -72x = -18x² +10x -72x +40 = -18x² -62x +40 = 2(-9x² -31x +20) ou -2(9x² +31x -20)
l) (9-3y)(6-5y) = 54 -45y -18y +15y² = 15y² -45y -18y +54 = 15y² -63y +54 = 3(5y² -21y +18) ou -3(-5y² +21y -18)
