# Square Roots and Radicals 18

Taught by YourMathGal
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Lesson Summary:

In this lesson on Square Roots and Radicals, Part 18, the focus is on rationalizing denominators when binomials containing square roots are involved. The concept of conjugates is introduced, and students are taught to multiply the numerator and denominator by the conjugate of the denominator to obtain a rational number in the denominator. Through examples, such as finding the conjugate of 2 minus the square root of 7 or solving 5 over square root of 11 minus 2 square root of 2, this lesson teaches students a key trick to solving rationalization problems.

Lesson Description:

Part 18 covers rationalizing the denominator when binomials containing square roots are in the denominator. Defines conjugates.

More free YouTube videos by Julie Harland are organized at http://yourmathgal.com

• How do you rationalize the denominator of a fraction when it contains a radical binomial expression?
• How do you simplify and rationalize the denominator of 1/(3 - square root of 2)?
• What is the conjugate of a radical binomial expression?
• Why does multiplying by the conjugate of a radical binomial get rid of square roots?
• Why does (5 + square root of 7)(5 - square root of 7) equal 18?
• Why does ((3*square root of 2) - 4)((3*square root of 2) + 4) equal 2?
• Why does (square root of 7 - square root of 2)(square root of 7 + square root of 2) equal 5?
• How do you find the conjugate of a radical binomial?
• How do you simplify and rationalize the denominator of 5/(square root of 11 - 2 * square root of 2)?
• #### Staff Review

• Currently 4.0/5 Stars.
This lesson continues to step up the difficulty of radical problems. This time, instead of just a single term root in the denominator of a fraction, there are binomial radical expressions in the denominator. You will learn how to multiply by the conjugate of the radical binomial in the denominator to get rid of it. This is a very important lesson to watch in what can be a very complicated and confusing lesson for students.