\(\eqalign{& P\left( x \right) = \left( {{x^2} - 1} \right) + \left( {x + 1} \right)\left( {x - 2} \right) \cr & P\left( x \right) = \left( {x - 1} \right)\left( {x + 1} \right) + \left( {x + 1} \right)\left( {x - 2} \right) \cr & P\left( x \right) = \left( {x + 1} \right)\left( {x - 1 + x - 2} \right) \cr & P\left( x \right) = \left( {x + 1} \right)\left( {2x - 3} \right) \cr} \)
