ACT Math : Arithmetic

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #1 : Simplifying Square Roots

Which of the following is the most simplified form of:

 

Possible Answers:

Correct answer:

Explanation:

First find all of the prime factors of 

So 

Example Question #2 : How To Simplify Square Roots

What is  equal to?

Possible Answers:

Correct answer:

Explanation:

 

1. We know that , which we can separate under the square root:

 

2. 144 can be taken out since it is a perfect square: . This leaves us with:

This cannot be simplified any further.

Example Question #1 : How To Simplify Square Roots

Which of the following is equal to ?

Possible Answers:

Correct answer:

Explanation:

When simplifying square roots, begin by prime factoring the number in question. For , this is:

Now, for each pair of numbers, you can remove that number from the square root. Thus, you can say:

Another way to think of this is to rewrite  as . This can be simplified in the same manner.

Example Question #8 : Exponents And Roots

Which of the following is equivalent to ?

Possible Answers:

Correct answer:

Explanation:

When simplifying square roots, begin by prime factoring the number in question. This is a bit harder for . Start by dividing out :

Now,  is divisible by , so:

 is a little bit harder, but it is also divisible by , so:

With some careful testing, you will see that 

Thus, we can say:

Now, for each pair of numbers, you can remove that number from the square root. Thus, you can say:

Another way to think of this is to rewrite  as . This can be simplified in the same manner.

Example Question #1 : How To Simplify Square Roots

What is the simplified (reduced) form of ?

Possible Answers:

It cannot be simplified further.

Correct answer:

Explanation:

To simplify a square root, you have to factor the number and look for pairs. Whenever there is a pair of factors (for example two twos), you pull one to the outside.

Thus when you factor 96 you get

Example Question #1 : Simplifying Square Roots

Which of the following is equal to ?

Possible Answers:

Correct answer:

Explanation:

When simplifying square roots, begin by prime factoring the number in question. For , this is:

Now, for each pair of numbers, you can remove that number from the square root. Thus, you can say:

Another way to think of this is to rewrite  as . This can be simplified in the same manner.

Example Question #801 : New Sat

Simplify the following square root: 

Possible Answers:

The square root is already in simplest form.

Correct answer:

The square root is already in simplest form.

Explanation:

We need to factor the number in the square root and find pairs of factors inorder to simplify a square root.

Since 83 is prime, it cannot be factored.

Thus the square root is already simplified.

Example Question #11 : Exponents And Roots

Right triangle  has legs of length . What is the exact length of the hypotenuse?

Possible Answers:

Correct answer:

Explanation:

If the triangle is a right triangle, then it follows the Pythagorean Theorem. Therefore:

 ---> 

At this point, factor out the greatest perfect square from our radical:

Simplify the perfect square, then repeat the process if necessary.

Since  is a prime number, we are finished!

Example Question #51 : Basic Squaring / Square Roots

Simplify: 

Possible Answers:

Correct answer:

Explanation:

There are two ways to solve this problem. If you happen to have it memorized that  is the perfect square of , then    gives a fast solution.

If you haven't memorized perfect squares that high, a fairly fast method can still be achieved by following the rule that any integer that ends in  is divisible by , a perfect square.

Now, we can use this rule again:

Remember that we multiply numbers that are factored out of a radical.

The last step is fairly obvious, as there is only one choice:

Example Question #11 : Simplifying Square Roots

Simplify: 

Possible Answers:

Correct answer:

Explanation:

A good method for simplifying square roots when you're not sure where to begin is to divide by  or , as one of these generally starts you on the right path. In this case, since our number ends in , let's divide by :

As it turns out,  is a perfect square!

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