Use the factorization method which is the cross-multiplication method. The first column should always be something squared, second should be a number and third should be an algebraic number. So, a x a gives you a-squared and 3 positive x 2 positive gives you 6 positive. Cross multiply them to get 5a after addition. Your answer will then be the equation that i have bracketed in the picture. To check if the answer is correct, use the expand method. You should get the same equation as before.