1. =2(x2-2xy+y2-16)
=2((x-y)2-42)
=2(x-y-4)(x-y+4)
2. =5(x2-2.1/10.x+1/100-y2+2.1/10y-1/100)
=5.((X-1/10)2-(Y-1/10)2)
=5(X-1/10-Y+1/10)(X-1/10+Y-1/10)
=5(X-Y)(X+Y-2/10)
3. =(X2-9XY+81/4Y2)-1/4Y2
=(X-9/2Y)^2-1/4Y^2
=(X-9/2Y-1/2Y)(X-9/2Y+1/2Y)
(X-5Y)(X-4Y)
4. =4X^2(X+Y)-(X+Y)
=(X+Y)(4X^2-1)
=(X+Y)(2X-1)(2X+1)