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Unformatted text preview: in the final term
into one which can’t be done!
So, there is a general rule of thumb in dealing with square roots of negative numbers. When
faced with them the first thing that you should always do is convert them to complex number. If
we follow this rule we will always get the correct answer.
So, let’s work this problem the way it should be worked. (2 - )( ) -100 1 + -36 = ( 2 - 10i )(1 + 6i ) = 2 + 2i - 60i 2 = 62 + 2i The rule of thumb given in the previous example is important enough to make again. When faced
with square roots of negative numbers the first thing that you should do is convert them to
There is one final topic that we need to touch on before leaving this section. As we noted back in
the section on radicals even though 9 = 3 there are in fact two numbers that we can square to
get 9. We can square both 3 and -3.
The same will hold for square roots of negative numbers. As we saw earlier -9 = 3 i . As with
square roots of positive numbers in this case we are really asking what did we square to get -9?
Well it’s easy enoug...
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- Spring '12