Posted by Shealyn on Sunday, February 1, 2009 at 7:29pm.
8/(sqrt2 + 4)
multiply top and bottom by (sqrt 2 -4) to get rid of the sqrt on the bottom because remember:
(a-b)(a+b) = a^2 - b^2
thereby squaring any square roots that might have been in b
8/(sqrt 2 + 4) * (sqrt 2-4)/(sqrt 2-4)
= 8 (sqrt 2 - 4) / [ (sqrt 2)^2 - 16 ]
= (8 sqrt 2 - 32) / [2-16]
= (8 sqrt 2 - 32) / -14
= (16 - 4 sqrt 2 / 7
By the way your math book did the
(a-b)(a+b) by FOIL
a^2 + ab -ab - b^2 which is a^2-b^2
but I know and you should know that
(a-b)(a+b) = a^2 - b^2
without going through the FOIL
Squareroot of A* square root of AB ^2
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