A (2x+1)²-5²=(2x+1+5)(2x+1-5)=(2x+6)(2x-4)=2(x+3)2(x-2)=4(x+3)(x-2)
B
(2x+1)²-(2x+3)²=
(2x+1+2x+3)(2x+1-2x-3)=(4x+4)(-2)=-8(x+1)
C
2(x-2)²-2(x-8)+(1-x)(1+x)=
2(x²+4-4x)-2x+16+1-x²=
2x²+8-8x-2x+17-x²=
x²-10x+25=
(x-5)²
D
(3(x-5))²-16(x²-4x+1)=
(3x-15)²-16(x²-4x+1)=
9x²+225-90x-16x²+64x-16=
-7x²-26x+209