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When the denominator of a fraction is a sum or difference with square roots, we use the Product of Conjugates pattern to rationalize the denominator.
When we multiply a binomial that includes a square root by its conjugate, the product has no square roots.
Simplify: .
Multiply the numerator and denominator by the conjugate of the denominator. | |
Multiply the conjugates in the denominator. | |
Simplify the denominator. | |
Simplify the denominator. | |
Remove common factors from the numerator and denominator. | |
We leave the numerator in factored form to make it easier to look for common factors after we have simplified the denominator. |
Simplify: .
Multiply the numerator and denominator by the conjugate of the denominator. | |
Multiply the conjugates in the denominator. | |
Simplify the denominator. | |
Simplify the denominator. | |
Simplify. |
Simplify: .
Multiply the numerator and denominator by the conjugate of the denominator. | |
Multiply the conjugates in the denominator. | |
Simplify the denominator. |
Simplify: .
Multiply the numerator and denominator by the conjugate of the denominator. | |
Multiply the conjugates in the denominator. | |
Simplify the denominator. | |
We do not square the numerator. In factored form, we can see there are no common factors to remove from the numerator and denominator. |
Access this online resource for additional instruction and practice with dividing and rationalizing.
Divide Square Roots
In the following exercises, simplify.
Rationalize a One-Term Denominator
In the following exercises, simplify and rationalize the denominator.
Rationalize a Two-Term Denominator
In the following exercises, simplify by rationalizing the denominator.
A supply kit is dropped from an airplane flying at an altitude of 250 feet. Simplify to determine how many seconds it takes for the supply kit to reach the ground.
A flare is dropped into the ocean from an airplane flying at an altitude of 1,200 feet. Simplify to determine how many seconds it takes for the flare to reach the ocean.
ⓐ Simplify
and explain all your steps.
ⓑ Simplify
and explain all your steps.
ⓒ Why are the two methods of simplifying square roots different?
Answers will vary.
ⓐ After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.
ⓑ After looking at the checklist, do you think you are well-prepared for the next section? Why or why not?
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