What causes a solution to a rational equation to be an extraneous solution

If a solution results in zero when substituted into the denominator of the equation, the solution is extraneous.

Answer with explanation:

While solving the rational equation we check the solution whether they are true solutions or are extraneous solution.

The true solutions are one which are solution of the rational equation as well as is a well defined solution of the equation. whereas the extraneous solution are one which are solution but does not satisfy the equation i. e. these are the excluded value of the equation which makes the denominator of the rational equation equal to zero.