Find the GCF 3xy , 21x^2 , 15x^3y

Since ${\displaystyle 3xy,21x^2,15x^{3}y}$ 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 ${\displaystyle 3xy,21x^2,15x^{3}y}$:

1. Find the GCF for the numerical part ${\displaystyle 3,21,15}$

2. Find the GCF for the variable part ${\displaystyle x^1,y^1,x^2,x^3,y^1}$

3. Multiply the values together

Find the common factors for the numerical part:

List all the factors for ${\displaystyle 3,21,15}$ to find the common factors.

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

${\displaystyle 21}$: ${\displaystyle 1,3,7,21}$

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

The common factors for ${\displaystyle 3,21,15}$ are ${\displaystyle 1,3}$.

The GCF for the numerical part is ${\displaystyle 3}$.

Next, find the common factors for the variable part:

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

x

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

y

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

The factors for ${\displaystyle x^3}$ are ${\displaystyle x\cdot x\cdot x}$.

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

y

List all the factors for ${\displaystyle x^1,y^1,x^2,x^3,y^1}$ to find the common factors.

The common factor for the variables ${\displaystyle x^1,y^1,x^2,x^3,y^1}$ is ${\displaystyle x}$.

x

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