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Double sqr root

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Re: Double sqr root

by mjjking » Wed Feb 25, 2009 6:19 am
billyr wrote:[(9+(80)^1/2)^1/2 + (9-(80)^1/2)^1/2]^2=?




Can somebody help me solve that one?


thanks
[(9+(80)^1/2)^1/2 + (9-(80)^1/2)^1/2]^2=

=(9+(80)^1/2)+(9-80^1/2)+[2(9+80^1/2)(9-80^1/2)]=
=18+2(81-9(80^1/2)+9(80^1/2)=
=18+162-160=20

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by BuckeyeT » Wed Feb 25, 2009 6:24 am
(a + b)^2 = a^2 + 2ab + b^2
(a^(1/2))^2 = a
Let 9 + (80^(1/2)) = a and 9 - (80^(1/2)) = b

= 9 + 80^(1/2) + 2 (9 + (80^(1/2)))(9 - (80^(1/2))) + 9 - 80^(1/2)
= 18 + 2 (9 + (80^(1/2)))(9 - (80^(1/2)))
Multiply out the 2ab area...
= 18 + 2 (81 - 80^(1/2) + 80^(1/2) - 80)
= 18 + 2 (81 - 80)
= 18 + 2 (1)
= 20.
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Re: Double sqr root

by sureshbala » Wed Feb 25, 2009 6:49 am
billyr wrote:[(9+(80)^1/2)^1/2 + (9-(80)^1/2)^1/2]^2=?
Can somebody help me solve that one?
thanks

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