Find AB

Discussion in 'Geometry and Trigonometry' started by nycmathguy, Sep 19, 2021.

  1. nycmathguy

    nycmathguy

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    Elementary College Geometry
    Question 5 Page 7

    View attachment 464

    AB = BC

    x^2 - 10 = 3x

    x^2 - 3x -10 = 0

    Solving for x, I got x = -2, x =5.

    I know that AB is distance and so AB must be positive.

    I will test each x-value to see which one yields a positive value.

    AB = x^2 -10

    Let x = -2

    AB = (-2)^2 - 10

    AB = 4 -10

    AB = -6. . .reject

    Let x = 5

    AB = (5)^2 - 10

    AB = 25 - 10

    AB = 15
     
    nycmathguy, Sep 19, 2021
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  2. nycmathguy

    MathLover1

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    correct
     
    MathLover1, Sep 19, 2021
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    nycmathguy likes this.
  3. nycmathguy

    nycmathguy

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    Cool. Precalculus tomorrow.
     
    nycmathguy, Sep 19, 2021
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