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Find the critical numbers by setting the first derivative equal to zero and solving for the x value(x)
A critical number cannot be obtained using the first derivative. Critical values also exist where f(x) is not defined. Therefore there will be a critical number at x=5.
If f'(x)>0 the function is increasing in the interval.
If f'(x)<0 the function is decreasing in the interval.
Choose a value less than 5.
f'(4)=-5 Since f'(4)<0 the function is decreasing in the interval
Choose a value greater than 5.
f'(6)=-5 Since f'(6)<0 the function is decreasing in the interval (5, `oo).`
Because the direction of the function did not change, there are NO relative extrema.
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