SAT Mathematics : Functions

Study concepts, example questions & explanations for SAT Mathematics

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Example Questions

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Example Question #9 : Understanding Functions

The polynomial function  has zeroes at  and . Which of the following could be the graph of  in the  plane?

Possible Answers:

Functiongraph113

Functiongraph111

Functiongraph112

Functiongraph114

Correct answer:

Functiongraph111

Explanation:

On a problem such as this that asks you to match a graph with a function, you need to use process of elimination using the characteristics of the function that you were provided. Here you're told where the zeroes are, meaning that at those points,  and , the graph should cross the x-axis. Only one graph meets those criteria, so you have your correct answer.

Example Question #10 : Understanding Functions

If n is a constant in the function f(x) = nx + 5, and f(14) = -2, what is f(2)?

Possible Answers:

4

Correct answer:

4

Explanation:

In this instance, we can use the outcome of the function when our input is 14 to solve for “n” and thus, understand our full function. If

 

f(14) = -2 and f(x) = nx + 5, then

 

n(14) + 5 = -2

 

If we isolate n, we arrive at 

 

n(14) = -7

 

 

Be careful… we can’t stop here! The question hasn’t asked us to solve for n, it has asked us for f(2). So, if we know that our function, with n as a known constant, is

 

, then

 

, or 4.

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