is decreasing on and is decreasing on . Therefore, is decreasing on
features
Completely analyze
The natural domain is all real numbers except and , which make the denominator equal to . These are singularities of . Otherwise, is continuous. There are no discontinuities.
Domain =
The graph will help us with the range, so we’ll wait on that.
has zeros at and . These make the numerator equal to . These are represented on the graph with and
The graph will have vertical asymptotes and . will change sign over , since the multiplicity is odd even . will not change sign over , since the multiplicity is odd even .
is a rational function and the degree of the denominator is greater than less than the degree of the numerator. Therefore,
The graph has a horizontal asymptote at .
From this, we can sketch a graph of .
Both zeros have odd multiplicity, therefore the graph must go below the -axis between them. There must be a local minimum. From the graph we can estimate that the critical number is approximately . is a local minimum. With some Calculus tools, we may be able to get an exact value.
has no global maximum or minimum.
has no local maximum.
- decreases on .
- decreases on .
- increases on .
- decreases on .
The graph makes it evident that the range is all real numbers.
With some graphing tools, we can get a better approximation of the critical number.
The critical number is approximately and the local minimum value of is approximately .
Completely analyze .
The domain is restricted by the square root to be .
The formula is a product, therefore the zeros come from each factor.
The factor of gives a zero of .
The factor of gives a zero of .
Since is always nonnegative, the sign of is the same as the sign of .
- is negative on
- is positive on
From this, we can sketch a graph of .
Our sketch suggest a global maximum between and .
If we had the derivative, then we could identify this critical number exactly. Currently, we’ll need a graph to approximate values.
- has a local and global maximum of at .
- has a local minimum of at .
- has no global minimum.
- is increasing on .
- is decreasing on .
Finally, the range is approximately .
The graph has no vertical asymptotes,
We do have alternatives to the derivative for some types of functions.
Earlier, we saw an algebraic method of identifying the critical number in the previous example.
We think there is a hump in the graph of and at the highest point, , the tangent line would be horizontal.
Now, create a new function called .
As we saw earlier, since we have a tangent line, the difference of the original function and the linear function has a double root at . divides evenly into . And, the resulting function then also has as a root.
First, factor out from .
divides into this evenly leaving
is a root of this, which means is a root of the numerator.
The zero we are looking for is . The critical number is and .
- has a local and global maximum of at .
- has a local minimum of at .
- has no global minimum.
- is increasing on .
- is decreasing on .
Finally, the range is .
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more examples can be found by following this link
More Examples of Function Analysis