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 Post subject: Question Number 97 in essentials course prep book?Posted: Tue Mar 15, 2011 5:38 pm

Joined: Tue Mar 15, 2011 5:08 pm
Posts: 2
Hello Veritas,
I am going over my notes. I did not right down the correct solution for question 97 in the essentials course prep supplement. I couldn't find it in the books either so if it is explained in books or On-demand please point me in that direction.

In section 7.3:

( sqrt(8+sqrt63 + sqrt(8-sqrt63 )^2

having a really tough time answer key says ans is C. 18

Thanks again,
John

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 Post subject: Re: Question Number 97 in essentials course prep book?Posted: Tue Mar 15, 2011 6:32 pm

Joined: Thu Feb 12, 2009 6:32 pm
Posts: 497
a = sqrt(8 + sqrt(63))

b = sqrt(8 - sqrt(63))

(a + b)^2 = a^2 + 2ab + b^2

= (8 + sqrt(63)) + 2 * sqrt(8 + sqrt(63)) * sqrt(8 - sqrt(63)) + (8 - sqrt(63))

= 8 + sqrt(63) + 2 * sqrt(8 + sqrt(63)) * sqrt(8 - sqrt(63)) + 8 - sqrt(63)

= 16 + 2 * sqrt ( (8 + sqrt(63)) * (8 - sqrt(63) )

= 16 + 2 * sqrt( 64 - 63)

= 18

- Veritas Help

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 Post subject: Re: Question Number 97 in essentials course prep book?Posted: Tue Mar 15, 2011 7:36 pm

Joined: Tue Mar 15, 2011 5:08 pm
Posts: 2
Thanks now I can finally go to sleep. Epic fail on that problem its been driving me nuts I knew you had to foil it but I was doing it wrong.

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