Answer
Fill the blank with$\quad +5$
Work Step by Step
With the foil method, with m and n being integers, we find that
$(x+m)(x+n)=x^{2}+(m+n)x+ mn,$
so ,the sum of mn is the coefficient of x, and
m and n are factors of the constant term.
Reversing, when we want to factor $x^{2}+bx+c,$ we search for two integers, m and n such that
their sum is b,
their product is c.
---
Here, we are given $b=-1, c=-30$ , and one of the integers is m=$-6$.
The other must be n=$+5$, since
$(-6)\cdot(+5)=-30,\quad (-6)+(5)=-1$
Fill the blank with$\quad +5$
