`a,5x^((x-1))-3x^((x-1))`
`=x^((x-1))(5-3)`
`=x^((x-1)).2`
`b,x(x+y)-5x-5y`
`=x(x+y)-(5x+5y)`
`=x(x+y)-5(x+y)`
`=(x+y)(x-5)`
`c, x^2-9=x^2-3^2=(x-3)(x+3)`
`d,4x^2-25``=(2x)^2-5^2=(2x-5)(2x+5)`
`e, x^6-y^6`
`=(x^2)^3-(y^2)^3`
`= (x^2+y^2)(x^4-x^2y^2+y^4)`