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: Basic square root question

  1. Dec 13, 2005 #1


    User Avatar

    suppose you have square root of -16 times square root of -25 (in separate square root symbols).

    would the answer be:

    a) no solution - cant have negative square roots

    b) 4i times 5i which equals 20i^2 which is -20

    c) -16 times -25 which is +400, then the square root of that is 20

    which one is correct?
  2. jcsd
  3. Dec 13, 2005 #2


    Staff: Mentor

    Exponentiation has a higher precedence than multiplication, just like multiplication has a higher precedence than addition. You therefore have to evaluate the roots before evaluating the multiplication.

  4. Dec 13, 2005 #3


    User Avatar

    so it should be choice b?
  5. Dec 13, 2005 #4


    User Avatar
    Science Advisor

    Assuming you are using the principle roots, yes.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook