Posted by **Megan** on Friday, November 4, 2011 at 3:18pm.

Rationalize the denominator: 5 /4-squareroot 5

(five over four minus square root five)

Please explain

- Algebra -
**Steve**, Saturday, November 5, 2011 at 5:38pm
since (a-b)(a+b) = a^2 - b^2,

(4-sqrt(5))(4+sqrt(5) = 16-5 = 11

so, multiply top and bottom by 4+sqrt(5) to get

5(4+sqrt(5))/11 = (20 + 5sqrt(5))/11

- Algebra -
**Megan**, Saturday, November 5, 2011 at 10:00pm
Thank you so much!! It really helped me understand!

## Answer This Question

## Related Questions

- Algebra - I need to rationalize the denominator of 2/3 square root of five, (...
- Algebra - True or False and please explain so that I can understand. 1. The ...
- Algebra - Rationalize each expression by building perfect nth root factors for ...
- Math help plz ASAP. - Rationalize each denominator. 6 + square root of 2 ...
- math - 1.0 Four square root of seven open bracket two square root of three plus ...
- math - Simply: (a) Four multiply by square root of seven open bracket two ...
- College Algebra help please - I need some help with a handful of questions. I ...
- College Algebra - I need some help with a handful of questions. I need to see ...
- College Algebra - I need some help with a handful of questions. I need to see ...
- Mathematics - what is (5 3/5 divided by 1 5/9) - (1 1/5) squared? what is (five ...

More Related Questions