5(2x-3)²-(5x-2)(5x+2)=5(4x²-12x+9)-(25x²+10x-10x-4)=20x²-60x+45-25x²+4=-5x²-60x+49
8(2x-1)(2x+1)-4(3x-1)²=8(4xé+2x-2x-1)-4(9x²-6x+1)=32x²-8-36x²+24x-4=-4x²+24x-12
factoriser:
(5x-1)-2(5x-1)(x+3)=(5x-1)[1-2(x+3)]=(5x-1)(1-2x-6)=(5x-1)(-2x-5)
9x²-24x+16=(3x-4)²
9(x-1)²-16(x+a)²
a²-b²=(a-b)(a+b)
3²(x-1)²-4(x+a)² = [3 (x-1)]²- [4 (x+a )]² = [3(x-1) - 4(x+a] [3(x-1)+4(x+a)]
=( 3x-3 - 4x -4a) (3x-3+4x+4a)= ( -x -3-4a )(7x-3+4a)
