Algebra

angala

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Jun 27, 2010
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Ok I really need help on this. Can anybody help me Rationalize the denominator of (14)/(3+sqrt(2))?
 
angala said:
Ok I really need help on this. Can anybody help me Rationalize the denominator of (14)/(3+sqrt(2))?

Use

\(\displaystyle (a + b)\cdot (a - b) \ = \ a^2 - b^2\)

so

\(\displaystyle (3 + \sqrt{2})\cdot (3 - \sqrt{2}) \ \ = \ \ 3^2 - (\sqrt{2})^2\) <<< Corrected "sign"

\(\displaystyle \frac{14}{3+\sqrt{2}}\)

\(\displaystyle = \ \ \frac{14}{3+\sqrt{2}} \cdot \frac{3-\sqrt{2}}{3-\sqrt{2}}\)

\(\displaystyle = \ \ \frac{14\cdot (3-\sqrt{2})}{3^2-2}\)

\(\displaystyle = \ \ 2\cdot (3-\sqrt{2})\)
 
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