Répondre :
A=(3x-4)² -(6x+-7)=9x²-24x+16-6x+7=9x²-30x+23
B=(7/5x+4/7)²=(49/25)x²+(8/5)x+16/49
C=(2x+5)(5x-1)(3x+2)=(10x²+23x-5)(3x+2)=30x^3+89x²+31x-10
A=(3x-4)² -(6x+-7)=9x²-24x+16-6x+7=9x²-30x+23
B=(7/5x+4/7)²=(49/25)x²+(8/5)x+16/49
C=(2x+5)(5x-1)(3x+2)=(10x²+23x-5)(3x+2)=30x^3+89x²+31x-10