Exercice 6

On regroupe les termes semblables, c'est-à-dire ceux qui contiennent la même puissance de $x$ :

a) $3x^2+5x-2x^2+7x-1=(3-2)x^2+(5+7)x-1=\boxed{x^2+12x-1}$

b) $4x-7+2x^2-3x+9=2x^2+(4-3)x+(-7+9)=\boxed{2x^2+x+2}$

c) $-x^2+6x-4x^2-x=(-1-4)x^2+(6-1)x=\boxed{-5x^2+5x}$

d) $2x^2-3x+5-x^2+3x-5=(2-1)x^2+(-3+3)x+(5-5)=\boxed{x^2}$

e) $7x^2-2x+1-7x^2+2x=(7-7)x^2+(-2+2)x+1=\boxed{1}$

f) $x^2+x+x^2+x=(1+1)x^2+(1+1)x=\boxed{2x^2+2x}$

g) $-3x+4x^2-2+x-4x^2=(4-4)x^2+(-3+1)x-2=\boxed{-2x-2}$

h) $5x^3-2x^2+x^3+3x^2=(5+1)x^3+(-2+3)x^2=\boxed{6x^3+x^2}$