1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Solve radical equation

  1. Feb 3, 2008 #1
    Could a tutor check my solution to my radical question? It is enclosed in this attachment as a word document.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution

    Attached Files:

  2. jcsd
  3. Feb 3, 2008 #2
    Your attachment needs to be approved. Either way, it's still pretty dangerous to open word attachments.

    Type it up and we'll take a look at it.
  4. Feb 3, 2008 #3


    User Avatar
    Science Advisor

    Why don't check your own answer? Just put your answer back into the original equation and do the arithmetic.
  5. Feb 3, 2008 #4
    You can plug your answer back into the equation to see if it works out. Its absolutely correct & absolutely wrong all at the same time. Can you figure out why? Plug your values back in & see why I said what I said. Your first step contains an algebra error, also think factoring for the first step.
  6. Feb 5, 2008 #5
    Is this correct?

    3x + x*sqrt(5) = 2


    (3x + x*sqrt(5)) = 2

    I factored out the x
    x (3 + sqrt(5)) = 2

    Divide both sides by sqrt(5) + 3
    x (3 + sqrt(5) / (sqrt(5) + 3) = (2) / (sqrt(5) + 3)


    x = (2) / (sqrt(5) + 3) final answer

    Is this correct?
    Last edited: Feb 5, 2008
  7. Feb 5, 2008 #6
    3x + x√5 = 2

    ²√5 = 5^½
    3x + (5^½)x = 2

    i get the same
    Last edited: Feb 5, 2008
  8. Feb 6, 2008 #7


    User Avatar
    Science Advisor

    Yes, that is correct. You could make it look nicer by "rationalizing the denominator": multiply both numerator and denominator by [itex]\sqrt{5}- 3[/itex] and you get
    [tex]x= \frac{2\sqrt{5}- 6}{2}= \sqrt{5}- 3[/itex]

    By the way, none of these are really "radical" equations since they don't involve roots of the unknown number. [itex]\sqrt{5}[/itex] is just another number!

    Oh, and there are no "tutors" here. Just us folks.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook