Extraneous solutions are roots of the polynomial which when substituted to the expression, the expression is invalid or not true. One example is x - 6 =. We square both sides, x^2 - 12x + 36 = x. <span> x^2 - 13x + 36 = 0. This is equal to (x-4)*(x-9) = 0. The roots are 9 and 4. The extraneous solution is 4 since when we substitute 4 to the original expression, there is no equality. </span>
In math, an extraneous solution is a solution of an equation that is obtained from solving the problem however this solution is not a valid solution. For instance, <span><span>(1/(x − 2)) </span>+ (<span>1/(x + 2)) </span>= <span>4 / <span><span>(x − 2)</span><span>(x + 2)
</span></span></span></span><span><span>(<span>x−2</span>)</span>+<span>(<span>x+2</span>)</span>=<span>4 x = 2
But <span>2</span><span> is excluded from the domain of the original equation because it would make the </span>denominator<span> of one zero and this is not valid.</span> </span></span>