GRE Math : How to add square roots

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #12 : Square Roots And Operations

Simplify: 

 

Possible Answers:

None of the other answers

Correct answer:

Explanation:

Take each fraction separately first:

(2√3)/(√2) = [(2√3)/(√2)] * [(√2)/(√2)] = (2 * √3 * √2)/(√2 * √2) = (2 * √6)/2 = √6

Similarly:

(4√2)/(√3) = [(4√2)/(√3)] * [(√3)/(√3)] = (4√6)/3 = (4/3)√6

Now, add them together:

√6 + (4/3)√6 = (3/3)√6 + (4/3)√6 = (7/3)√6

Example Question #1 : How To Add Square Roots

Compare the quantities.

Quantity A: 

Quantity B: 

Possible Answers:

Quantity B is larger.

The relationship cannot be determined from the information given.

Quantity A is larger.

The two quantities are equal.

Correct answer:

The two quantities are equal.

Explanation:

Begin by breaking down each of the roots in question.  Often, for the GRE, your answer arises out of doing such basic "simplification moves".

Quantity A

This is the same as:

, which can be reduced to:

Quantity B

This is the same as:

, which can be reduced to:

Thus, at the end of working through the proper math, you realize that the two values are equal!

Example Question #3 : How To Add Square Roots

Simplify the following expression: 

Possible Answers:

Correct answer:

Explanation:

Begin by factoring out each of the radicals:

For the first two radicals, you can factor out a  or :

The other root values cannot be simply broken down. Now, combine the factors with :

This is your simplest form.

Example Question #36 : Basic Squaring / Square Roots

Solve for .

Note, :

Possible Answers:

Correct answer:

Explanation:

Begin by getting your  terms onto the left side of the equation and your numeric values onto the right side of the equation:

Next, you can combine your radicals. You do this merely by subtracting their respective coefficients:

Now, square both sides:

Solve by dividing both sides by :

Example Question #622 : Gre Quantitative Reasoning

Simplify the following expression: 

Possible Answers:

Correct answer:

Explanation:

To solve this problem, we must realize that the only way to add or subtract square roots is if the number under to square root is equivalent to each other. Therefore we must find a way to simplify each square root.

First we attempt to simplify the first term,

We break apart the number under the square root and find

Simplifying

Therefore we know that in order to try and simplify the other terms, the number under the square root has to be 3. By removing  from the other terms in the equation, we will attempt to see if they can be simplified as well.

For the second term,

Finally for the last term,

 

Our new equation becomes 

Once all number under the square roots become the same, we can treat it as simple addition/subtraction and solve.

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