Since fractions cannot be subtracted, we will need to find the least common denominator.  In order to find the least common denominator, we will need to multiply the  and .

There is no number below this value where the factors of nine and sixteen will intersect.

The question only asked for the least common denominator, so we do not need to evaluate this.

The least common denominator is .

When there are two terms involved in a denominator, I like to look at each separately and combine at the end. For 2 and 7, the least common denominator is what thier product is, which is 14. Then, for and , is the LCD for that pair since it's the least common multiple of the two. Now, put your answers together to get: .

The least common denominator is found by finding what the least common multiple is.

The multiples of  are 

The multiples of  are 

The multiples of  are 

The lowest number that occurs in the three numbers listed is , which means you could add or subtract the fractions by converting them all to fractions with a denominator of .

To solve this equation, we must find the least common denominator to add the fractions.

Keep in mind that the denominator of the second term is the difference of squares, which can be rewritten as

This is the least common denominator.

Now, we multiply both sides of the equationby the LCD on top and bottom (this is essentially 1):

After canceling terms, we get

Now, we solve for x:

Let's first get all the known terms on one side of the equation:

We need to find a common denominator for all the fractions.  One easy way to do this is to multiply each fraction by the denominator on the other two:

We can now add the numerators together:

And simplify:

The least common denominator would be all of the denominators multiplied together:

To find the Least Common Denominator, we multiply the denominator of both terms together:

In order to solve for the least common denominator, multiply both denominators together.

This will require the FOIL method.

Simplify the right side.

The answer is:  

In order to find the least common denominator, one of the ways to find it is to write out the factors for each number.  We are trying to find the least number possible that is divisible by all the numbers of the denominators.

Write out the factors for all the numbers.  Notice that the number must be at least greater than  because of the four and five in the second and third fractions.

The number  is divisible by all three numbers.

The answer is:  

The least common denominator is the lowest number that is divisible by all the denominators in the expression.  Write out some of the factors of each denominator.

Notice that each factor shares twenty as the common denominator and can be converted to this denominator to solve.

The answer is: