We are given : 5a^2-25a
Please note: We always check Greatest Common Factor (GCF) first when factoring a polynomial.
If Greatest Common Factor (GCF) exist we factor out GCF.
In the given polynomial, we can see that greatest common factor of 5a^2 and 25a is 5a.
So, we would factor out GCF 5a first.
In order to factor out GCF, we need to divide all terms of the polynomila by GCF we got.
If we factor out 5a from 5a^2 -25a, we need to divide 5a^2 and -25a by 5a.
On dividing 5a^2 by 5a we get a and
on dividing -25a by 5a we get -5.
Therefore, on factoring out 5a, we get
5a(a-5).
Therefore, we use Greatest Common Factor (GCF) method of factoring.