Find the GCF 15a^2b-30ab

Since ${\displaystyle 15a^{2}b,-30ab}$ contain both numbers and variables, there are two steps to find the GCF (HCF). Find GCF for the numeric part then find GCF for the variable part.

Steps to find the GCF for ${\displaystyle 15a^{2}b,-30ab}$:

1. Find the GCF for the numerical part ${\displaystyle 15,-30}$

2. Find the GCF for the variable part ${\displaystyle a^2,b^1,a^1,b^1}$

3. Multiply the values together

Find the common factors for the numerical part:

List all the factors for ${\displaystyle 15,-30}$ to find the common factors.

${\displaystyle 15}$: ${\displaystyle 1,3,5,15}$

${\displaystyle -30}$: ${\displaystyle -30,-15,-10,-6,-5,-3,-2,-1,1,2,3,5,6,10,15,30}$

The common factors for ${\displaystyle 15,-30}$ are ${\displaystyle 1,3,5,15}$.

The GCF for the numerical part is ${\displaystyle 15}$.

Next, find the common factors for the variable part:

The factors for ${\displaystyle a^2}$ are ${\displaystyle a\cdot a}$.

The factor for ${\displaystyle b^1}$ is ${\displaystyle b}$ itself.

b

The factor for ${\displaystyle a^1}$ is ${\displaystyle a}$ itself.

a

The factor for ${\displaystyle b^1}$ is ${\displaystyle b}$ itself.

b

List all the factors for ${\displaystyle a^2,b^1,a^1,b^1}$ to find the common factors.

The common factors for the variables ${\displaystyle a^2,b^1,a^1,b^1}$ are ${\displaystyle a\cdot b}$.

The GCF for the variable part is ${\displaystyle ab}$.