so you always want to pull out the gcf first but since there isn't one, we can move on.
so we can make an acb chart which is multiplying the a value and the c value and find factors that of that product that will equal the b value.
a value is 2
c value is -15
b value is 7
-30 factors to equal 7 = 10, -3
10 - 3 = 7
so the factors 10 and -3 work.
so now you make 2 separate parenthesis with one of the factors and one x. and it should be set equal to 0.
(x+10)(x-3) = 0
now solve for x in each separate parenthesis.
x = -10
x = 3
those r the roots
hope this helps