Set the denominator in equal to to find where the expression is undefined.

Factor using the AC method.

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.

If any individual factor on the left side of the equation is equal to , the entire expression will be equal to .

Set the first factor equal to and solve.

Set the first factor equal to .

Add to both sides of the equation.

Set the next factor equal to and solve.

Set the next factor equal to .

Subtract from both sides of the equation.

The final solution is all the values that make true.

The equation is undefined where the denominator equals , the argument of a square root is less than , or the argument of a logarithm is less than or equal to .

Find Where Undefined/Discontinuous (3x-15)/(x^2-x-20)