posted by -Untamed- on .
About rationalizing denominator, is it true that you can't always multiply by the same square root denominator to get a perfect square?
yes, because (√n)² = n
so, multiplying the root by itself gets rid of the root.
If the denominator is not just a root, but something like √m + n, then you need to multiply by √m - n, since
(√m + n)(√m - n) = m - n²
also, you sometimes have to use
(√m + √n)(√m - √n) = m - n