Bonjour,

Développer l'expression:

D= (5x-1)(5x-2)-(2x+3)(5x-1)

D= 25x²-5x-10x+2- (10x²+15x-2x-3)

D= 25x²-15x+2- 10x²-13x+3

D= 15x²-28x+5

Factoriser:

D= (5x-1)(5x-2)-(2x+3)(5x-1)

D= (5x-1)(5x-2-2x - 3) ***changement de signe

D= (5x-1)(3x-5)

Calculer D pour x= 5/3:

D= 15x²-28x+5

D(5/3)= 15(5/3)²-28(5/3)+5= 15(25/9)-140/3+5= 375/9-3(140)/9+9(15)/9

D(5/3)=    375/9- 420/9+ 135/9= 90/9=  10