The 7x is the addition term and the 2 is the multiplication term.
You have to factor the 3x^2
There is only one factor for 3x^2 which is (3x ) and (x )
you have to factor the 2 which also only has one factor and it is 2 and 1
Now you have to place each into the parenthesis
(3x +1) ( x+ 2)