Factorise x^2 + 4x +3

First take the 4x - the two numbers that will be +/- to the x in the brackets will need to add to form this number, so the possibilities are 1 and 3 or 2 and 2.Now take the 3 - the two numbers that will be +/- to the x in the brackets will need to multiply to form this number, so 1 and 3.The number in combination in common is 1 and 3, giving us the answer (x+1)(x+3)