Solve By Factoring

Discussion in 'Other Pre-University Math' started by nycmathguy, Jul 12, 2021.

  1. nycmathguy

    nycmathguy

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    Set 1.3
    Question 33

    See attachment.

    Isn't it better to solve for x using the quadratic formula in terms of question 33?

    20210712_161348.jpg
     
    nycmathguy, Jul 12, 2021
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  2. nycmathguy

    MathLover1

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    x^2+(2sqrt(5))x+5=0....you can write 5 as sqrt(5)^2
    x^2+(2sqrt(5))x+sqrt(5)^2=0............recognize square of the sum (a+b)^2=a^2+2ab+b^2

    then you have

    (x + sqrt(5))^2=0....factor
    (x + sqrt(5)) (x + sqrt(5))=0

    solution:
    (x + sqrt(5))=0 => x =- sqrt(5))
     
    MathLover1, Jul 12, 2021
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    nycmathguy likes this.
  3. nycmathguy

    nycmathguy

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    I will post a few more like this one to get practice.
    Where did (x + sqrt{5}) come from?
     
    nycmathguy, Jul 12, 2021
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    MathLover1 likes this.
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