Bonjour,
Développer:
A= (2x-3)²- 7x ( 2x -3)
A= 4x²-6x-6x+9-14x²+21x
A= - 10x²+9x+9
Factoriser:
A= (2x-3)²- 7x ( 2x -3)
A= (2x-3)(2x-3-7x)
A= (2x-3)(-5x-3)
A= - (2x-3)(5x+3)
et remplace x par 3/5
A(3/5)= - 10(3/5)²+9(3/5)+9
A(3/5)= - 10(9/25)+ 5*27/25+25*9/25
A(3/5)= 270/25
A(3/5)= 54/5