Results 1 to 3 of 3

Thread: help

  1. #1
    Member
    Joined
    May 2005
    From
    I LIVE IN QUEBEC,CANADA
    Posts
    82

    help

    √5(2√20+√2)
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor Quick's Avatar
    Joined
    May 2006
    From
    New England
    Posts
    1,024
    Quote Originally Posted by blame_canada100 View Post
    √5(2√20+√2)
    do you mean this: $\displaystyle \sqrt{5}(2\sqrt{20}+\sqrt{2})$


    If so, then start by finding the perfect squares: $\displaystyle \sqrt{5}(2\sqrt{4\cdot 5}+\sqrt{2})$

    Then spread them out: $\displaystyle \sqrt{5}(2\sqrt{4}\sqrt{5}+\sqrt{2})$

    Then simplify: $\displaystyle \sqrt{5}(4\sqrt{5}+\sqrt{2})$

    Now distribute: $\displaystyle 4\sqrt{5}\sqrt{5}+\sqrt{2}\sqrt{5}$

    Now combine together: $\displaystyle 4\sqrt{25}+\sqrt{10}$

    Now simplify: $\displaystyle 4\cdot 5+\sqrt{10}$

    Therefore: $\displaystyle \boxed{ \sqrt{5}(2\sqrt{4\cdot 5}+\sqrt{2})=20+\sqrt{10}}$
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    12,028
    Thanks
    848
    Hello, blame_canada100!

    Simplify: .$\displaystyle \sqrt{5}\left(2\sqrt{20} + \sqrt{2}\right)$

    Multiply: .$\displaystyle \underbrace{(\sqrt{5})(2\sqrt{20})} + \underbrace{(\sqrt{5})(\sqrt{2})} $

    . . . . . . . $\displaystyle = \;2\sqrt{100} \quad+ \quad\sqrt{10}$

    . . . . . . . $\displaystyle =\;\; 2\cdot 10 \quad+ \quad\sqrt{10}$


    Answer: . $\displaystyle 20 + \sqrt{10}$

    Follow Math Help Forum on Facebook and Google+


/mathhelpforum @mathhelpforum