Exercice 2:
Développer les expressions suivantes:
a) 5x*(-2x)=-10x²
b) 2x-7x=-5x
c) 2y²-4y+7-8y²+12= (2y²-8y²)-4y+(7+12)
= -2y²-4y+19
d) (2x+3x)*(-2-5)= 5x*(-7)
= -35x
e) (-3x²)*(-4y)= 12x²y
f) 2n*4+4n(-5n)-4n*(-2)= 8n-20n+8n
= -4n
Exercice 3:
A=4x(6-3x)= (4x*6)+(4x*(-3x))
= 24x-12x²
=-12x²+24
B=6-2t-(4t-8)= 6-2t-4t+8
= -6t+14
C=-(7x+8)+3(3x-5)= -7x-8+9x-15
= 2x-23
D=3y-(4y-2) 6= 3y-(24y-12)
= 3y-24y+12
= -21y+12
E=4x²+(2x-5)(3+7x)=4x²+2x*3+2x*7x+(-5)*3+(-5)*7x
=4x²+6x+14x²-15-35x
=10x²-29x+15
