SAT II Math I : Functions and Graphs

Study concepts, example questions & explanations for SAT II Math I

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Example Questions

Example Question #122 : Solving And Graphing Exponential Equations

Does the function  have any -intercepts? 

Possible Answers:

Yes, 

No 

Yes,  and 

Yes, 

That cannot be determined from the information given. 

Correct answer:

No 

Explanation:

The -intercept of a function is where . Thus, we are looking for the -value which makes .

If we try to solve this equation for  we get an error.

To bring the exponent down we will need to take the natural log of both sides.

Since the natural log of zero does not exist, there is no exponent which makes this equation true.

Thus, there is no -intercept for this function. 

Example Question #31 : Solving Exponential Functions

Which of the following correctly describes the graph of an exponential function with a base of three?

Possible Answers:

It begins by decreasing gradually and then decreases more quickly. 

It starts out by gradually increasing and then increases faster and faster. 

It stays constant. 

It begins by decreasing quickly and then levels out. 

It starts by increasing quickly and then levels out. 

Correct answer:

It starts out by gradually increasing and then increases faster and faster. 

Explanation:

Exponential functions with a base greater than one are models of exponential growth. Thus, we know that our function will increase and not decrease. Remembering the graph of an exponential function, we can determine that the graph will begin gradually, almost like a flat line. Then, as  increases,  begins to increase very quickly. 

Example Question #32 : Solving Exponential Functions

Solve:  

Possible Answers:

Correct answer:

Explanation:

The base of the right side can be rewritten as base two.

Simplify the equation.

Add  on both sides.

Subtract 3 on both sides.

Divide by 20 on both sides.

 

The answer is:  

Example Question #31 : Solving Exponential Functions

Solve:  

Possible Answers:

Correct answer:

Explanation:

To solve, change the base of the fraction to base 4.

With similar bases, we can set the powers equal.

Add one on both sides.

Divide by 2 on both sides.

The answer is .

Example Question #34 : Solving Exponential Functions

Solve:  

Possible Answers:

Correct answer:

Explanation:

Rewrite the right side as base 2.

Replace the term into the equation.

With similar bases, we can set the exponents equal.

Subtract six from both sides.

Divide by negative three on both sides.

The answer is:  

Example Question #1 : Solving Rational And Fractional Functions

Simplify:

Possible Answers:

Correct answer:

Explanation:

Raise a fraction to a negative power by raising its reciprocal to the power of the absolute value of the exponent. Then apply the properties of exponents as follows:

Example Question #2 : Solving Rational And Fractional Functions

Simplify 

Possible Answers:

Correct answer:

Explanation:

To simplify this problem we need to find the least common denominator between the two fractions. To do this we look at 5 and at 8. The least common number between these two is 40.

In order to rewrite each fraction in terms of a denominator of 40 we need to muliple as follows:

we are able to mulitply by 8/8 and 5/5 because those fractions are really just 1 written in a different format.

Now using order of opperations we get the following

Now we have a common denominator and can do our addition to get the simplfied number:

Example Question #1 : Least Common Denominator In Fractions

Solve the following equation to find

Possible Answers:

Correct answer:

Explanation:

In order to be able to find , we must first find the least common denominator. In this case, it is 

The equation can now be written as:

Solving for , we get: 

Example Question #1 : Least Common Denominator

What's the least common denominator of  and ?

Possible Answers:

Correct answer:

Explanation:

When finding the least common denominator, the quickest way is to multiply the numbers out.

In this case  and  share a factor other than  which is . We can divide those numbers by  to get  and  leftover.

Now, they don't share a common factor so basically multiply them out with the shared factor. Answer is .

 

Another approach is to list out the factors of both number and find the factor that appears in both sets first.

We can see that  appears in both sets before any other number thus, this is our answer.

 

Example Question #4 : Solving Rational And Fractional Functions

Simplify the following:

Possible Answers:

 

Correct answer:

 

Explanation:

To simplify the sum of the two fractions, we must find the common denominator.

Simplifying the denominator of the first fraction, we get

because the denominator is a difference of two squares, which follows the form

Now, we can rewrite the sum as

It is far easier to see the common denominator now:

 

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