To rationalize the denominator meansto eliminate any type of radical expression in the denominator such as square roots and cube roots. The crucial idea is to main point the original portion by an appropriate value, such that after simplification, the denominator no longer consists of radicals.

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Note: In this lesson, we will certainly only emphasis on square roots for the services of simplicity.

When the denominator is a monomial, the straightforward strategy is to apply the truth that


Conjugate that a Binomial

On the various other hand, if the denominator is a binomial, the id of conjugate comes in handy. The conjugate the a binomial is same to the binomial itself, however, the center sign is changed or switched.

Here space some instances of binomials with their equivalent conjugates. But much more importantly, observe that the product of a given binomial and its conjugate is an expression there is no the radical symbol.

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Let’s walk over part examples!

Examples of exactly how to Rationalize the Denominator

Example 1: Rationalize the denominator large5 over sqrt 2 . Simplify further, if needed.

The denominator has a radical expression,the square root of 2. Eliminate the radical in ~ the bottom by multiplying by itself which is sqrt 2 due to the fact that sqrt 2 cdot sqrt 2 = sqrt 4 = 2 .

However, by doing so we readjust the “meaning” or worth of the original fraction. Come balance the out, carry out the same thing on top by multiplying through the exact same value.

What we room doing below is multiplying the original fraction by largesqrt 2 over sqrt 2 which is just identical to 1.

Remember thatany number, once multiplied come 1, gives earlier the initial number, thus, we adjust the form but no the original an interpretation of the number itself!

So climate the straightforward solution to this problem is shown below.

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The final answer consists of a denominator there is no a radical symbol, and also so us can claim that we have successfully rationalized it.

Example 2:Rationalize the denominator large6 over sqrt 3 . Then simplify if necessary.

Observethat the denominator has a square source of 3. We have the have to rationalize that by gaining rid that the radical symbol.


Thatmeans we should multiply the original fraction by largesqrt 3 over sqrt 3 .

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Yes, the radical symbol in ~ thebottom is gone however we have the right to still do something. Simplify more by canceling out typical factors.

Example 3: Rationalize largesqrt 27 over 12.

What we have here is a square root of whole fraction. The first step is to use the Quotient preeminence of Square Roots. This allows us to generate a portion with a distinct numerator and also denominator with radical symbols.


By using the dominion above,we get a difficulty that is much more familiar to us.

The “new” kind of the given problem has a denominator the root 12 ,so we will multiply it by largesqrt 12 over sqrt 12 .

As you can see, ns did no multiply with the radicals top top the numerator due to the fact that the number will thrive larger, therefore more difficult to simplify. This way we should have the ability to simplify the numerator fairly easily due to the fact that the radicands room smaller as soon as they are kept asis.

Example 4: leveling by rationalizing the denominator oflarge7sqrt 10 over sqrt 2 .

Multiply both the numerator and denominator by sqrt 2 . By law so, the radical in the denominator must go away.

We can’t stop right here just yet since the radical expression in the numerator contains a perfect square factor. Let’s store going through our simplification.

Cancel out usual factors to gain the final answer. Girlfriend seethat large14 over 2 = 7.

Example 5: leveling by rationalizing the denominator oflarge6 - sqrt 5 over sqrt 8 .

This time the numerator has a binomial. There’s really no difference in the strategy because the denominator is still a monomial.We will multiply theoriginal fraction by the denominator, sqrt 8 .

Make sure to distribution sqrt 8 right into the terms within the parenthesis.

The numerator have the right to be additional simplified since the radicands have perfect square factors. Observe that 8 = 4 imes 2 and also 40 = 4 imes 10 whereby the aspect 4left( 4 = 2^2 ight) is a perfect square number.

Example 6: Rationalize large2 over 3 + sqrt 3 .

This trouble is a small bit different because the denominator is currently a binomial, containing 2 terms. To get rid of the radical in the denominator, we room going to multiply the top and bottom by the conjugate of the provided denominator.

How perform we get the conjugate of the denominator? take it the same denominator however switch the center sign.

The center sign the the initial denominator switches from confident to negative. Our selection of multiplier that deserve to rationalize the denominator is large3 - sqrt 3 over 3 - sqrt 3 .

Here goes our solution.

Example 7:Rationalize large3 over 2 - sqrt 2 .

The denominator has actually a negative sign in the middlewhich makes the conjugate to have a positive middle sign.

The multiplier to usage inorder come rationalize the denominator is

Here goes our solution.

No common factors between the numerator and also denominator, thusthis is our last answer.

Example 8: Rationalize largesqrt 7 over - 3 - sqrt 7 .

The given denominator is

which renders its conjugate to be

Given the problem:
Multiplythe numerator and denominator of the original portion by the conjugate the the denominator.
Distribute the numerators, and also FOIL the denominators.
The center terms of the denominator will drop out because they space the “same” in values however opposite in signs.Simplify the roots of perfect square numbers, i.e.sqrt 49 = 7.
Subtract thevalues in the denominator, 9 - 7 = 2.
If possible, reduce the portion to its shortest terms. It looks prefer there’s nothing come cancel out in between the top andbottom. Therefore, store this together our last answer.

Example 9: Rationalize largesqrt 6 - sqrt 2 over sqrt 6 + sqrt 2 .

Reverse the center sign the the denominator to achieve its conjugate.That means, the conjugate of sqrt 6 + sqrt 2 is sqrt 6 - sqrt 2 .

Multiply both top and also bottom through the conjugate.
After broadening using FOIL, the middle terms that the numerator will certainly be added, while the middleterms the the denominator will certainly be canceled.
Simplify the roots of perfect square numbers in every opportunityAdd or subtract the totality numbers that come the end after gaining the square source of perfect square numbers.
At this point, simplify

Remember to rest it down as a product wherein one of its components is a perfect square number.

Obviously, 12 = 4 imes 3. This is aperfect an option of factors since the number 4 is a perfect square.
Rewrite radical 12 as the productof the radicals that its factors.
We understand that the square root of 4 equals 2!
Simplify by multiplication
The numerator has actually a common factor the 4. That indicates we couldpull the end a element of 4 outside the parenthesis.
Cancel common factors between the numerator and denominator
Write the last answer.

Example 10: Rationalize largesqrt 2 + sqrt 8 over - sqrt 2 - sqrt 8 .

Multiply the given fraction, both top and bottom, through the conjugate that the denominator.
Expand the binomials utilizing the silver paper method.Cancel out terms that room the “same” but opposite in signs.
Get the exact values of the square root of perfect square numbers.
Perform the compelled arithmetic to work in both numerator and also denominator.
Cancel out common factors.The numerator and also denominator is both divisible through 6.

See more: What Does The Prefix Mis Mean, What Is A Word With The Prefix Mis

Write the last answer.

Practice through Worksheets

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