`1-8x+16x^{2}-y^{2}`
`=1^{2}-2.1.4x+(4x)^{2}-y^{2}`
`=(1-4x)^{2}-y^{2}`
`=(1-4x-y)(1-4x+y)`
1 - 8x + 16x2 - y2
= (16x^2 - 8x + 1) - y^2
= (4x - 1)^2 - y^2
= (4x - 1 - y) (4x - 1 + y)
`1-8x+16x^2-y^2`
`= ( 16x^2 - 8x + 1 ) - y^2`
`= [ (4x)^2 - 2 . 4x . 1 + 1 ] - y^2`
`= (4x-1)^2 - y^2`
`= (4x-y-1).(4x+y-1)`