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-   -   Adding and subtracting radical expressions (https://www.askmehelpdesk.com/showthread.php?t=330051)

  • Mar 16, 2009, 02:31 PM
    dingolove09
    adding and subtracting radical expressions
    yes this is my homework... v.v..

    1) √63 + √175 + √112
    2) √28x + √63x
    3) √45 + √180
    4) √52 - √1300
    5) 5√98 - 3√32
    6) √32 + √128
    7) √147 + 6√3
    8) √168 + √42
    9) 5√17 + 17√5
    10) 6√3 + √300
    11) -2√3b + √27b
    12) 4√2m + 6√3m - 4√2m
    13) √50m + √72m
    14) √16z + 2√8z - 3√z
    15) √216t + √96t
    16) 4√52x + √117x - 2√13
    17) 3√96k + 2√180
  • Mar 16, 2009, 02:48 PM
    jordan1989
    You need to factor the radicand of each radical down to the prime factorization. If you get a pair of factors, pull it outside the radicand as a coefficient. Add the coefficients.
  • Mar 16, 2009, 02:52 PM
    dingolove09

    I'll try it, I get lost when it comes to coefficients
  • Mar 16, 2009, 02:53 PM
    jordan1989
    Try the first problem, and post the answer here. I'll let you know if you've done it correctly or not.
  • Mar 16, 2009, 03:05 PM
    dingolove09

    √63 + √175 + √112

    √3*21 √5*35 √4*28

    3√21 5√35 4√28


    Am I right so far?. I don't know
  • Mar 16, 2009, 03:12 PM
    jordan1989
    You're right so far, but you need the prime factorization. You should end up with the same radicand, so they can be added.

    Let me complete the first one for you, so you can see how it's done:

    We have √63 + √175 + √112

    √63 = √3 X 3 X 7. There's a pair of 3's and a 7 left over, so pull out the 3 to make 3√7

    √175 = √5 X 5 X 7. There's a pair of 5's and a 7 left over, so pull out the 5. 5√7

    √112 = √2 X 2 X 2 X 2 X 7. We have 2 pairs of 2's, so that becomes 4. 4√7

    3 + 5 + 4 = 12. So the final answer is 12√7
  • Mar 16, 2009, 03:20 PM
    dingolove09

    So I just need to find the prime factorization of the radicands?
  • Mar 16, 2009, 03:24 PM
    jordan1989
    Yes, that's all you need to do. Pair up any pairs of factors and pull them out, and anything left over (singles)would be left under the radicand.
  • Mar 16, 2009, 03:27 PM
    dingolove09

    Oh OK, well thank you

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