Rational Inequality...1

Discussion in 'Other Pre-University Math' started by nycmathguy, Oct 3, 2021.

  1. nycmathguy

    nycmathguy

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    Section 2.7
    Question 42

    20210930_232249.jpg

    (x^2 - 1)/x < 0

    Replace < with the equal sign.

    x • (x^2 - 1)/x = 0 • x

    x^2 - 1 = 0

    (x - 1)(x + 1) = 0

    Setting each factor to zero, the key numbers are clearly x = -1 and x = 1.

    Plot on the real number line and test the original rational inequality per interval.

    <----------(-1)---------------(1)--------------->

    When x = -2, we get-3/2 < 0. True statement.

    When x = -1, we get 0 < 0. False statement.

    When x = 0, we get -1/0 which is undefined.

    When x = 1, we get 0/1 < 0. False statement.

    When x = 2, we get 3/2 < 0. False statement.

    The only interval that satisfies the original inequality is (-infinity, -1).

    Here is the solution set on the real number line:

    20211002_194749.jpg

    You say?
     
    nycmathguy, Oct 3, 2021
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  2. nycmathguy

    MathLover1

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    that is one solution and it's correct ( x<-1)
    other solution is 0<x<1

    so interval notation for both solutions: ( infinity, -1), (0, 1)
     
    MathLover1, Oct 3, 2021
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  3. nycmathguy

    nycmathguy

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    Can you break it step by step? How did you get two solution sets? In fact, I will watch a few rational inequality clips on You Tube.
     
    nycmathguy, Oct 3, 2021
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  4. nycmathguy

    MathLover1

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    (x^2 - 1)/x < 0

    if (x^2 - 1)< 0 => solutions: x<1 or x<-1

    denominator cannot be equal to zero, we exclude zero and solution is 0<x<1
    combine x<-1 and 0<x<1
    interval:
    ( infinity, -1), (0, 1)
     
    MathLover1, Oct 3, 2021
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  5. nycmathguy

    nycmathguy

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    I gotta watch video clips to grasp this stiff. Thanks anyway.
     
    nycmathguy, Oct 3, 2021
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