Find the critical numbers of f (x) = x^2-6x. Find also the open intervals on which the function is increasing or decreasing and locate all relative extrema.
Solution:
A number a in the domain of a given function f is called a critical number ‘(a) = 0 or f ‘ is undefined at x = a.
Relative extrema are the minimums or maximum points on a part of a curve, while absolute extrema are the minimums and maximum points along the entire curve.
Now we are looking at the following curve:
f (x) =
To find the extrema, we take the first derivative and figure out at what value of x, the first derivate of the function equals to zero:
f’(x) = 2x-6
f’(3) = 0
As you can see the function is decreasing from negative infinity to 3, and increasing from 3 to infinity. The critical number is 3. There is only one relative (or local) minimum at (3, -9).
Posted in 12th Grade, Homework Answers, Physics Answers.
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