Cours Développer, identitiés remarquables

Exercice : développer

L'énoncé

Cet exercice revient sur la notion de double distributivité que l'on voit au collège. C'est une notion fondamentale.

Développer chacune de ces expressions.


Question 1

\(A = (-8x+3)(5+x)\)

\(A = (-8x+3)(5+x)\)
\(A = -40x -8x^2+15 + 3x\)
\(A = -8x^2-37x+15\)

Question 2

\(B = (6-3x)(7-x)\)

\(B = 3x^2-6x-21x+42\)
\(B = 3x^2-27x+42\)

Question 3

\(C = (\dfrac{1}{2} x+1)(6x+2)\)

\(C = (\dfrac{1}{2}x+1)(6x+2)\)
\(C = 3x^2+x+6x+2\)

\(C = 3x^2+7x+2\)

Question 4

\(D = -3(x-6)+(5x-5)(2x-2)\)

\(D = -3x+18 +10x^2-10x-10x+10\)
\(D = 10x^2-23x+28\)

Question 5

\(E = (-2x-1)(7+4x) + (8x+3)(1+x)\)

\(E = -14x-8x^2-7-4x+8x+8x^2+3+3x\)
\(E = -7x-4\)