Sovi.AI - AI Math Tutor

Scan to solve math questions

QUESTION IMAGE

use the graph of y = f(x) to discuss the graph of y = f(x). organize yo…

Question

use the graph of y = f(x) to discuss the graph of y = f(x). organize your conclusions in a table, and sketch a possible graph of y = f(x). determine how the properties on different intervals of f(x) affect f(x). complete the table.

xf(x)f(x)
x = -2
-2 < x < 0
x = 0
0 < x < 2
x = 2
2 < x < ∞

sketch the graph of f(x). choose the correct graph

Explanation:

Step1: Recall derivative - function relationship

If \(f^{\prime}(x)>0\), \(f(x)\) is increasing. If \(f^{\prime}(x)<0\), \(f(x)\) is decreasing. If \(f^{\prime}(x)\) is increasing, \(f(x)\) is concave - up and if \(f^{\prime}(x)\) is decreasing, \(f(x)\) is concave - down.

Step2: Analyze \(-\infty

Since \(f^{\prime}(x)\) is positive and decreasing, \(f(x)\) is increasing and concave - down.

Step3: Analyze \(x=-2\)

When \(f^{\prime}(x)\) changes its behavior (from positive - decreasing to other values), \(f(x)\) may have an inflection point. Here, \(f^{\prime}(-2)\) is a local maximum of \(f^{\prime}(x)\), so \(f(x)\) has an inflection point at \(x = - 2\).

Step4: Analyze \(-2

If \(f^{\prime}(x)\) is positive and increasing in \(-2 < x<0\), then \(f(x)\) is increasing and concave - up.

Step5: Analyze \(x = 0\)

If \(f^{\prime}(0)=0\), \(f(x)\) has a horizontal tangent at \(x = 0\).

Step6: Analyze \(0

If \(f^{\prime}(x)\) is negative and increasing in \(0 < x<2\), then \(f(x)\) is decreasing and concave - up.

Step7: Analyze \(x = 2\)

If \(f^{\prime}(2)\) is a local maximum of \(f^{\prime}(x)\) (change in the behavior of \(f^{\prime}(x)\) from increasing to decreasing), \(f(x)\) has an inflection point at \(x = 2\).

Step8: Analyze \(2

If \(f^{\prime}(x)\) is negative and decreasing in \(2 < x<\infty\), then \(f(x)\) is decreasing and concave - down.

The completed table:

\(x\)\(f^{\prime}(x)\)\(f(x)\)
\(x=-2\)Local maximum of \(f^{\prime}(x)\)Inflection point
\(-2Positive and increasingIncreasing and concave - up
\(x = 0\)ZeroHorizontal tangent
\(0Negative and increasingDecreasing and concave - up
\(x = 2\)Local maximum of \(f^{\prime}(x)\)Inflection point
\(2Negative and decreasingDecreasing and concave - down

To sketch the graph of \(y = f(x)\):

  • Start with an increasing and concave - down curve for \(x\in(-\infty,-2)\).
  • At \(x=-2\), the curve has an inflection point and then becomes increasing and concave - up until \(x = 0\) where it has a horizontal tangent.
  • Then it becomes decreasing and concave - up until \(x = 2\) where it has another inflection point.
  • After \(x = 2\), it is decreasing and concave - down for \(x\in(2,\infty)\).

Answer:

\(x\)\(f^{\prime}(x)\)\(f(x)\)
\(x=-2\)Local maximum of \(f^{\prime}(x)\)Inflection point
\(-2Positive and increasingIncreasing and concave - up
\(x = 0\)ZeroHorizontal tangent
\(0Negative and increasingDecreasing and concave - up
\(x = 2\)Local maximum of \(f^{\prime}(x)\)Inflection point
\(2Negative and decreasingDecreasing and concave - down

Sketch as described above.