développer : A = (3x + 1)²-(4x + 3)² B = (2x + 1)-(4x + 3)-(3x+7)(x - 2) C = (3x - 2)²-2(x + 5)²
A=(9x^2+6x+1)-(16x^2+24x+9)
A=-7x^2-18x-8
B=(-2x-2)-(3x^2-6x+7x-14)
B=(-2x-2)-(3x^2+x-14) B= 3x^2-3x-12
C=(9x^2-8x+4)-2(x^2+10x+25)
C=9x^2-8x+4)-(2x^2-6x-24) C=7x^2-2x+28