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July 30, 2015

July 30, 2015

Posted by **G** on Tuesday, June 3, 2008 at 10:20am.

I used this for the redial sign \/

Problem:

30 \/15

_______

4 \/10

The book says the answer is 15/4 \/6 (15/4 with radicand of 6). I have tried to solve the problem several different ways. I do not arrive at this answer.

- Algebra -
**Reiny**, Tuesday, June 3, 2008 at 10:54amhow about this :

30√15 / (4√10)

= 15√3 / 2√5 now multiply top and bottom by √2

= 15√6 /4

- Algebra -
**G**, Tuesday, June 3, 2008 at 11:23amThank you for your response.

I did get 15\/3 and 2\/5. Why would you then mutiply by \/2?

The answer in the book is 15/4 with radicand of 4 not a radicand of 6. Are you also showing that there is a missprint in the book and the racdicand is 4?

I have several missprints int he book.

- Algebra -
**Reiny**, Tuesday, June 3, 2008 at 11:32amAt the top of your post you said the book answer was 15/4 with radicand of 6

and now you say it is 15/4 with radicand of 4 not a radicand of 6. ???

It is generally considered "poor form" to have a radical in the denominator

This goes back to pre-calculator times.

What would you rather have done back in 1950:

divide by √2 which would be dividing by 1.4142136...

or divide by 4 ?

- Algebra -
**Reiny**, Tuesday, June 3, 2008 at 11:34amBTW, I just noticed that my second last line in my solution is

15√3 / 2√5

that should have been

15√3 / 2√**2**

- Algebra -
- Algebra -
**G**, Tuesday, June 3, 2008 at 11:53amIf is 4 \/10. Why would it be 2 \/2 and not the 2 \/5?

- Algebra -
**Reiny**, Tuesday, June 3, 2008 at 11:58amOK, from the start:

30√15 / (4√10) divide top and bottom by 2√5

= 15√3 / 2√2 multiply top and bottom by √2

= 15√6 /4

- Algebra -

- Algebra -