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: Square root algebra question

  1. Aug 8, 2011 #1
    I found a way to find the square root of an expression which is confusing to me.
    Is anyone familiar to this method? And my main question... will it be useful?

    Attached Files:

    • math.jpg
      File size:
      14.7 KB
  2. jcsd
  3. Aug 8, 2011 #2


    User Avatar
    Homework Helper

    I am not familiar with this method. I found a http://www.youtube.com/watch?v=iz5c0DizXyk" that shows how to do a similar problem. It's not in English, though (Hindi?). But between the video and your attachment I was able to figure out how it works. As to whether or not this is useful, I personally don't find it useful, but others may have a different opinion.
    Last edited by a moderator: Apr 26, 2017
  4. Aug 8, 2011 #3


    Staff: Mentor

    I don't think this is very useful, either, and certainly not worth memorizing. What is much more useful is being able to factor perfect square trinomials such as x2 + 4x + 4 = (x + 2)2 and the like.
  5. Aug 8, 2011 #4
    By looking at the expression I would't have even guess it was a perfect square.. I thought it would have been something along the lines of....

    (cx + a)^4 .... with some type of coefficient infront of x.
  6. Aug 8, 2011 #5
    If you memorize (or can derive) a few lines of "Pascals Triangle", you can quickly figure out things like (x+y)^5 and so on. I found that worth learning.
  7. Aug 8, 2011 #6


    User Avatar
    Homework Helper

    Well, if the original polynomial ended up being a binomial raised to the 4th power, then the original polynomial would still be a perfect square, would it not? Using your notation,
    (cx + a)4 = [((cx + a)2]2, after all.

    But as it is, the original polynomial is not a binomial raised to the 4th power. If you rearrange the terms, the last one, 4a4, is NOT a perfect 4th-power. In other words, you can't write 4a4 as (ka)4, where k is an integer.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook