D>0 i.e. b^2-4ac>0 we get k^2>= 48(k square greater than or equal to 48) hence minimum natural no. Which satisfies it is 7 hence k=7 now the polynomial would look like 2x^2+7x+6 which can be written as 2x^2+4x+3x+6 i.e. 2x(x+2)+3(x+2) i.e. (2x+3)(x+2). Also tell me from where have you taken this question