DM EX1

1 a) (2x-3)²+(x-5)(x+5)=(4x²²+9-12x)+(x²-25)=5x²-12x-16

b)(2x+1)(-x-1)-(-2x+3)²=(-2x²+2x+1x-1)-(4x²-12x+9)=-2x²+2x-x-1-4x²+12x-9=-6x²+9x-10

2 a)(x-1)²-(2x-3)²=[(x-1)+(2x-3)][(x-1)-(2x-3)]=(3x-4)(3x+2)=9x²-18x+8=9x(x-2)+8

b)9x²+6x+3=3(3x²+2x+1)