I do not understand positive and negative intervals and increasing/decreasing intervals. I included 2 examples from my textbook which I did not understand and I was wondering if someone can explain it to me.(adsbygoogle = window.adsbygoogle || []).push({});

Example 1:

f(x) = 2 - x

x intercept is (2, 0) and y-intercept is (0,2)

f(x) is positive when xε(-∞, 2) and negative xε(2, ∞)

f(x) is decreasing when xε(-∞, ∞)

reciprocal od the function is g(x) = 1 / 2 - x

reciprocal function is positive when xε(-∞, 2) and negative xε(2, ∞)

It is increasing when xε(-∞, 2) and when xε(2, ∞)

Example 2:

f(x) = 9 - x^2

x-intercepts are 3 and -3

f(x) is positive when xε(-3, 3) and negative when xε(-∞, -3) and when xε(3, ∞)

f (x) is increasing when xε(-∞, 0) and decreasing when xε(0, ∞)

g(x) = 1 / 9- x^2

reciprocal function is positive when xε(-3, 3) and negative xε(-∞, -3) and when xε(3, ∞)

It is decreasing when xε(-∞, -3) and when xε( -3, 0) and increasing when xε(0, 3) and when xε(3, ∞)

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# Homework Help: How do you write positive and negative intervals, increasing/decreasing intervals

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