To divide by a fraction, multiply by its reciprocal.

Consider the form . Find a pair of integers whose product is and whose sum is . In this case, whose product is and whose sum is .

Write the factored form using these integers.

Rewrite as .

Since both terms are perfect squares, factor using the difference of squares formula, where and .

Factor out of .

Factor out of .

Factor out of .

Consider the form . Find a pair of integers whose product is and whose sum is . In this case, whose product is and whose sum is .

Write the factored form using these integers.

Cancel the common factor of .

Factor out of .

Factor out of .

Cancel the common factor.

Rewrite the expression.

Cancel the common factor of .

Factor out of .

Cancel the common factor.

Rewrite the expression.

Multiply and .

Raise to the power of .

Raise to the power of .

Use the power rule to combine exponents.

Add and .

Move to the left of .

Simplify ((a^2-a-6)/(a^2-81))÷((a^2-7a-18)/(4a+36))