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Surds & Irrational Equations

Purple Gorilla · 2009-10-14 14:28:16

Hey guys, We're currently doing Surds & Irrational Equations in class and I'm lost on a particular section. Could anyone help me with just 2 and then I'll try the rest on my own... The question says "Express each of the following fractions with a rational denominator" (The slash indicates a fraction) 3/4√2-1 And 5/2√7-√3…

14-10-2009 2:28pm

#1

Purple Gorilla

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Join Date: February 2009

Posts: 824

Hey guys,
We're currently doing Surds & Irrational Equations in class and I'm lost on a particular section. Could anyone help me with just 2 and then I'll try the rest on my own...

The question says "Express each of the following fractions with a rational denominator"

(The slash indicates a fraction)
3/4√2-1

And

5/2√7-√3

Could someone explain how to do them?
Thanks

0

Comments

#2 14-10-2009 4:17pm

Fremen

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Join Date: May 2006

Posts: 2356

just multiply above and below by the conjugate.
The idea is that

(a + √b)(a-√b)= a^2 + b

(check this).

0