Question 618981
"x+a is a factor" implies that -a is a root of the polynomial, i.e.


*[tex \LARGE a^2 - pa + q = a^2 - ma + n = 0]


Cancel the a^2 and we are left with


*[tex \LARGE -pa + q = -ma + n], isolate terms with "a" in it and factor.


*[tex \LARGE a(-p + m) = n - q \Rightarrow a = \frac{n-q}{m-p}]