1
(a+2b)²-(a-2b)²=(a+2b-a+2b)(a+2b+a-2b)=4b*2a=8ab
2
(x-4)²-2(x-4)(x+4)+(1+x)²=x²-8x+16-2x²+32+1+2x+x²=-6x+49
x=-3,4
-6*(-3,4)+49=20,4+49=69,4
3
-x(x-4)²-2x(x-4)(x+4)+4=-x³+8x²-16x-2x³+32x+4=-3x³+8x²+16x+4
4
125-x^6=(5-x²)(25+5x²+x^4)
5
2x(1+4x)(4x-1)=32x³-2x