Shenika factored the polynomial completely. what is the value of a?

5x3 + 35x2 + 6x + 42
(5x2 + a) (x + b)

This the concept of polynomial equations. To solve the given polynomial equation, we look for a random number such that when we substitute it in the equation we get a zero, in our case that number is x=-7,
5(-7)^3+35(-7)^2+6(-7)+42
=5(-343)+35(49)-42+42
=-1715+1715-42+42
=0
therefore one of our solution is:
x=-7
x+7=0
therefore to get the next solution we proceed as follows:
We divide the solution by the polynomial
(5x^3+35x^2+6x+42)/(x+7)
this will give us:
(5x^2+6)
this implies that
(5x^3+35x^2+6x+42)
=(x+7)(5x^2+6)
=(5x^2+6)(x+7)
hence it can be seen clearly that:
A=6 and B=7
the answer is:
A=6
B=7