\(\eqalign{
& 1)\,\,\,3{x^2} - 5x + 3xy - 5y \cr
& = \left( {3{x^2} + 3xy} \right) - \left( {5x + 5y} \right) \cr
& = 3x\left( {x + y} \right) - 5\left( {x + y} \right) \cr
& = \left( {x + y} \right)\left( {3x - 5} \right) \cr
& 2)\,\,2{x^2} - 4x + 4xy - 8y \cr
& = 2x\left( {x - 2} \right) + 4y\left( {x - 2} \right) \cr
& = 2\left( {x - 2} \right)\left( {x + 2y} \right) \cr
& 3)\,\,3{x^3} - 6x \cr
& = 3x\left( {{x^2} - 2} \right) \cr
& 4)\,\,\left( {x - 2} \right)\left( {y - 2} \right) \cr
& 5)\,\,2x\left( {{x^2} - 2y} \right) \cr} \)
