B= (x-2)(x+7)+x²
=x²+ 7x - 2x - 14 + x²
= 2x² + 5x - 14
C= 2x² + (x-4)(3-x)
= 2x² + 3x - x² - 12 + 4x
= x² + 7x -12
D= x(x+1)-3(x+1)
=x² + x - 3x -3
= x² - 2x -3
C= (2x+1)²
(rappel (a+b)²= a²+2ab+b²)
= 4x²+ 4x +1
D=(1+3x)²
=1+6x+9x²
E=(3x+2)²
= 9x²+12x+4
C=(3-x)²
rappel (a-b)²=a²-2ab+b²)
=9-6x+x²
D= (2x-1)²
=4x²-4x+1
E=(3-5x)²
=9-30x+25x²
C=(3x-1)(3x+1)
(rappel (a-b)(a+b)=a²-b²
=9x²-1
D=(2x+1)(2x-1)
=4x²-1
E=(5+3x)(5-3x)
=25-9x²
voilà si tu as une question n'hésite pas en espérant t'avoir aidé ;)
