Question 64847
To simplify:

(5)sqrt(5/7)-(2)sqrt(7/5)-sqrt(315) 

First, lets rewrite sqrt(315) as sqrt((9)(35)) or (3)sqrt(35). Now we have:

(5)sqrt(5/7)-(2)sqrt(7/5)-(3)sqrt(35) 

Now we'll multiply everything by the (sqrt(35))/sqrt(35) and we get

((5)sqrt(5/7))(sqrt(35))/sqrt(35)-((2)sqrt(7/5))(sqrt(35))/sqrt(35)-((3)sqrt(35))(sqrt(35))/sqrt(35) When we simply this, we get:

((5)sqrt(5))(sqrt(5))/sqrt(35)-((2)sqrt(7)(sqrt(7))/sqrt(35)-((3)sqrt(35)(sqrt35))/sqrt(35)  

further simplifying, we have:

((5)(5))/sqrt(35)-((2)(7))/sqrt(35)-((3)(35))/sqrt(35) simplifying again:

(25-14-105)/sqrt(35) or 

-94/sqrt(35) once again, we'll multiply by (sqrt(35))/sqrt(35) and we get

(-94)sqrt(35)/35

This is about simplified as I can get it. 

You can check the answer with a calculator 

Hope this helps.  Happy holidays---ptaylor