ACT Math : Basic Squaring / Square Roots

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #3 : 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 #51 : Basic Squaring / Square Roots

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 #12 : Simplifying Square 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 #14 : 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!

Example Question #15 : Simplifying Square Roots

Simplify: 

Possible Answers:

Correct answer:

Explanation:

Again here, if no perfect square is easily recognized try dividing by , or .

Note that the  we obtained by simplifying  is multipliednot added, to the  already outside the radical.

Example Question #16 : Simplifying Square Roots

Simplify:

Possible Answers:

Correct answer:

Explanation:

To solve, simply find a perfect square factor and pull it out of the square root.

Recall the factors of 48 include (16, 3). Also recall that 16 is a perfect square since 4*4=16.

Thus,

Example Question #17 : Simplifying Square Roots

Solve:

Possible Answers:

Correct answer:

Explanation:

The trick to these problems is to simplify the radical by using the following rule:   and  Here, we need to find a common factor for the radical. This turns out to be five because  Remember, we want to include factors that are perfect squares, which are what nine and four are. Therefore, we can rewrite the equation as: 

Example Question #52 : Basic Squaring / Square Roots

Simplify:

Possible Answers:

Correct answer:

Explanation:

When simplifying the square root of a number that may not have a whole number root, it's helpful to approach the problem by finding common factors of the number inside the radicand. In this case, the number is 24,300.

What are the factors of 24,300?

24,300 can be factored into:

When there are factors that appear twice, they may be pulled out of the radicand. For instance, 100 is a multiple of 24,300. When 100 is further factored, it is  (or 10x10). However, 100 wouldn't be pulled out of the radicand, but the square root of 100 because the square root of 24,300 is being taken. The 100 is part of the24,300. This means that the problem would be rewritten as:  

But 243 can also be factored: 

Following the same principle as for the 100, the problem would become
 because there is only one factor of 3 left in the radicand. If there were another, the radicand would be lost and it would be 9*10*3. 
9 and 10 may be multiplied together, yielding the final simplified answer of 

Example Question #1 : How To Find The Common Factors Of Squares

Possible Answers:

Correct answer:

Explanation:

To solve the equation , we can first factor the numbers under the square roots.

When a factor appears twice, we can take it out of the square root.

Now the numbers can be added directly because the expressions under the square roots match.

 

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