On considère : A=(5x-1)²-(5x-1)(x+3)
1) Developer et reduire A
2) Factoriser A
merci de bien vouloir m'aider
1) A= (5x-1)²-(5x-1)(x+3)
=25x²-10x+1-(5x²+15x-x-3)
=25x²-10x+1-5x²-15x+x+3
=20x²-24x+4
2) A=(5x-1)²-(5x-1)(x+3)
=(5x-1)(5x-1)-(5x-1)(x+3)
=(5x-1)(5x-1-x-3)
=(5x-1)(4x-4)