The solution given in the website:
Here's my solution:
What am I doing wrong?
$\endgroup$ 61 Answer
$\begingroup$Your method is correct, but you aren't quite finished. If you attempted to plug $-5$ back into the original equation, you would have:
$(-5)^{\frac{1}{2}}+3(-5)^{-\frac{1}{2}}=10(-5)^{-\frac{3}{2}}$
But those exponents involving halves are really square roots, and is $-5$ in the domain of the square root function? No. Thus that solution is extraneous.
$\endgroup$ 8
