`A_7 = 4x^2 - y^2 - 4x + 2y`

`= (4x^2 - y^2) - (4x - 2y)`

`= (2x - y)(2x + y) - 2(2x - y)`

`= (2x - y)(2x + y - 2)`

``

`A_8 = x^2 + 4x + 4 - 36y^2`

`= (x^2 + 4x + 4) - (6y)^2`

`= (x + 2)^2 - (6y)^2`

`= (x + 2 - 6y)(x + 2 + 6y)`

``

`A_9 = x^2 + 6x - 25y^2 + 9`

`= (x^2 + 6x + 9) - 25y^2`

`= (x + 3)^2 - (5y)^2`

`= (x + 3 - 5y)(x + 3 + 5y)`

``

`A_10 = 4x^2 + 4x - y^2 + 1`

`= (4x^2 + 4x + 1) - y^2`

`= (2x + 1)^2 - y^2`

`= (2x + 1 - y)(2x + 1 + y)`

`A_11 = x^2 + 4xy + 4y^2 - 1`
`= (x^2 + 4xy + 4y^2) - 1`
`= (x + 2y)^2 - 1^2`
`= (x + 2y - 1)(x + 2y + 1)`