SOLUTION: simplify 5 times the square root of 7/20 - 2 times the square root of 20/7 - 3 times the square root of 560

Algebra ->  Square-cubic-other-roots -> SOLUTION: simplify 5 times the square root of 7/20 - 2 times the square root of 20/7 - 3 times the square root of 560      Log On


   

Question 66032This question is from textbook An Incremental Development
: simplify
5 times the square root of 7/20 - 2 times the square root of 20/7 - 3 times the square root of 560 This question is from textbook An Incremental Development

Answer by ptaylor(2198) About Me  (Show Source):
You can put this solution on YOUR website!
simplify
5 times the square root of 7/20 - 2 times the square root of 20/7 - 3 times the square root of 560
5sqrt(7/20)-2sqrt(20/7)-3sqrt560=
5sqrt(7/20)-2sqrt(20/7)-3sqrt((20)(4)(7)) which equals:
5sqrt(7/20)-2sqrt(20/7)-6sqrt((20)(7))
We need a common denominator. We can get this by multiplying the numerator and denominator of each term by sqrt((20)(7)) --- the LCM. This gives us:
5(sqrt7)(sqrt7)-2(sqrt20)(sqrt20)-6(sqrt((20)(7))(sqrt((20)(7))) which equals:
[5(7)-2(20)-6(20)(7)]/sqrt((20)(7) simplifying we get:
(35-40-840)/sqrt(140)=-845/sqrt(140)
Multiply numerator and denominator by sqrt(140) to get rid of the radical in the denominator and we get:
-845sqrt(140)/140 =
-845sqrt((4)(35))/140=
-1690sqrt(35)/140= divide both numerator and denominator by 10
-169sqrt(35)/14
That should be it unless I made a mistake.
CK by using a calculator
Hope this helps---ptaylor