Interpreting Functions - Common Core: High School - Functions

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Screen shot 2016 01 06 at 11.12.11 am

Given the graph above of , which intervals represent where is increasing?

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This question is testing one's ability to grasp the relationship between the image a function creates graphically and the intervals where the function is increase, decreasing, positive, or negative. Problems like these are considered modeling problems because of their application. For example, the intercepts, extreme values, slope, symmetry, and end behavior for these functions mark key relationships between the inputs and the resulting outputs.

For the purpose of Common Core Standards, application of interpreting functions fall within the Cluster B of the function and use of function notation concept (CCSS.MATH.CONTENT.HSF-IF.B).

Knowing the standard and the concept for which it relates to, we can now do the step-by-step process to solve the problem in question.

Step 1: Identify what the question is asking.

This particular question is asking for where the function is increasing. It is important to understand that when a function is increasing, the graph exhibits a positive slope.

Step 2: Identify the intervals where the graph is positive (increasing) and where it is negative (decreasing).

Screen shot 2016 01 06 at 11.12.11 am

Looking at the above graph, there are two intervals where the graph is increasing and one interval where it is decreasing.

As the graph approaches from the left, the values increase. This means that the slope for this section of the graph is positive or increasing; therefore it is one of the intervals where the function is increasing.

Between the values of the values decrease. This means that the slope for this section of the graph is negative or decreasing.

From the value to infinity, the values increase. This means that the slope for this section of the graph is also positive or increasing; therefore it is another one of the intervals where the function is increasing.

Step 3: Answer the question.

is increasing on the intervals .