(rt2)/ (2rt5 - 3rt2)
I know that we multiply top and bottom by (2rt5 + 3rt2), but i want to know why? How do we know to do this?
Thanks.
Simplifying surds within a fraction...?
2016-08-11 7:26 pm
回答 (2)
2016-08-11 7:49 pm
Remember how to factor the difference of square:
a² - b² = (a+b) (a-b)
This comes in handy when a denominator has the form (√a-√b). Multiply the fraction by (√a+√b)/(√a+√b) so the denominator simplifies to a-b.
https://www.flickr.com/photos/dwread/28632219770/
a² - b² = (a+b) (a-b)
This comes in handy when a denominator has the form (√a-√b). Multiply the fraction by (√a+√b)/(√a+√b) so the denominator simplifies to a-b.
https://www.flickr.com/photos/dwread/28632219770/
2016-08-11 7:37 pm
√2
----------------
2 √5 - 3 √2
√2 [ 2√5 + 3√2 ]
-----------------------------------
[ 2 √5 - 3 √2 ] [ 2√5 + 3√2 ]
√2 [ 2√5 + 3√2 ]
-----------------------
20 - 18
√2 [ 2√5 + 3√2 ]
----------------------
2
in answer to the why? part -------it is to get rid off the √ sign.
----------------
2 √5 - 3 √2
√2 [ 2√5 + 3√2 ]
-----------------------------------
[ 2 √5 - 3 √2 ] [ 2√5 + 3√2 ]
√2 [ 2√5 + 3√2 ]
-----------------------
20 - 18
√2 [ 2√5 + 3√2 ]
----------------------
2
in answer to the why? part -------it is to get rid off the √ sign.
收錄日期: 2021-04-21 19:37:41
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20160811112615AA5oskG