This preview shows page 1. Sign up to view the full content.
Unformatted text preview: er and so we can’t
evaluate the radical of a negative number if the index is even. Note however that we can evaluate
the radical of a negative number if the index is odd as the previous part shows.
Let’s briefly discuss the answer to the first part in the above example. In this part we made the
claim that 16 = 4 because 4 2 = 16 . However, 4 isn’t the only number that we can square to get 16. We also have ( -4 ) = 16 . So, why didn’t we use -4 instead? There is a general rule
2 about evaluating square roots (or more generally radicals with even indexes). When evaluating
square roots we ALWAYS take the positive answer. If we want the negative answer we will do
© 2007 Paul Dawkins 17 http://tutorial.math.lamar.edu/terms.aspx College Algebra - 16 = -4
This may not seem to be all that important, but in later topics this can be very important.
Following this convention means that we will always get predictable values when evaluating
Note that we don’t have a si...
View Full Document
- Spring '12