ACT Math : Algebra

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #22 : Algebraic Functions

Alice is twice as old as Tom, but four years ago, she was three years older than Tom is now. How old is Tom now?

Possible Answers:

\dpi{100} \small 3

\dpi{100} \small 21

\dpi{100} \small 13

\dpi{100} \small 9

\dpi{100} \small 7

Correct answer:

\dpi{100} \small 7

Explanation:

The qustion can be broken into two equations with two unknows, Alice age \dpi{100} \small (A) and Tom's age \dpi{100} \small (T).

\dpi{100} \small A=2T

\dpi{100} \small A-4=T+3

\dpi{100} \small 2T-4=T+3

\dpi{100} \small T=7

Example Question #121 : Algebraic Functions

A jet goes from City 1 to City 2 at an average speed of 600 miles per hour, and returns along the same path at an average speed if 300 miles per hour. What is the average speed, in miles per hour, for the trip?

Possible Answers:

350miles/hour

300miles/hour

500miles/hour

450miles/hour

400miles/hour

Correct answer:

400miles/hour

Explanation:

Chose a number for the distance between City 1 and 2; 1800 works well, as it is a multiple of 600 and 300.

Now, find the time for each trip, the total distance, and the total time.

 

Now we can find the average speed by dividing the total distance by the total time.

Example Question #21 : How To Find F(X)

Find .

Possible Answers:

Correct answer:

Explanation:

Plug 5 into first:

Now, plug this answer into :

Example Question #21 : How To Find F(X)

If  and , what is ?

Possible Answers:

Correct answer:

Explanation:

Plug g(x) into f(x) as if it is just a variable. This gives f(g(x)) = 3(x– 12) + 7.

Distribute the 3: 3x– 36 + 7 = 3x– 29

Example Question #1201 : Algebra

If  and , then 

Possible Answers:

Correct answer:

Explanation:

To answer this question, we need to understand exactly what  actually means. 

We start from the inside of the parentheses and work outwards. Therefore, we first solve for  using the equation for  provided for us. So, for this data:

Therefore, . We now take that answer and plug it in for the  value within . So, for this data:

Therefore, the answer to  is .

Example Question #42 : Algebraic Functions

If , what does  equal?

Possible Answers:

Correct answer:

Explanation:

For a question like this, treat it just like you would the use of a numeric value for evaluating your function. All you do is “plug in” . Thus, for this function, you get:

Next, you just need to distribute everything correctly:

Example Question #31 : How To Find F(X)

If , what is ?

 

Possible Answers:

Correct answer:

Explanation:

For a question like this, treat it just like you would the use of a numeric value for evaluating your function. All you do is “plug in” . Thus, for this function, you get:

From here, you merely need to distribute correctly!

Example Question #52 : Algebraic Functions

When written in symbols, “The square of the sum of  and  equals ” is represented as:

Possible Answers:

Correct answer:

Explanation:

“The square of the sum” means that the summation of the terms is done first, and that summation is squared, which corresponds to the term .

Example Question #53 : Algebraic Functions

Given the functions  and , what is  when ?

Possible Answers:

Correct answer:

Explanation:

In order to find , work from the inside out. In other words, begin by finding , or  since 

Now, seeing as . Substitute  for  in  in order to find the answer. 

Example Question #54 : Algebraic Functions

Find  when , and .

Possible Answers:

Correct answer:

Explanation:

Start on the inside by finding  when

Now that we know , we can substitute  for  in

Find .

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