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113: Operations on Radicals - Rationalize Binomial

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Last updated over 5 years ago
13 Nsɛmmisa

Bell Assignment: multiply

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Mathematicians do not like radicals in denominators. So, we rationalize by multiplying by the conjugate.

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Finish first 14 sections of DelatMath.

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1.

(2-3\sqrt{6})(-5-\sqrt{6})

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2.

(5+\sqrt{7})(5-\sqrt{7})

Notes L6-5c: Rationalize Binomial Denominators

note: (a+b)(a-b) are called conjugates. Like [2], when conjugates are multipled together, the middle terms cancel.

Since we are working with square roots, we can use conjugates to eliminate the root.

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3.

Which is the conjugate of 9-\sqrt{5}?

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4.

Multiply together 9-\sqrt{5} and its conjugate.

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5.

Which is the conjugate of -3+\sqrt{11}?

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6.

Multiply together -3+\sqrt{11} and its conjugate.

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7.

To rationalize \LARGE \frac{-2}{-8+\sqrt{6}}

you would:

  1. Simplify both the numerator and denominator.

  2. Find the conjugate.

  3. Reduce if possible.

  4. Distibute (by foiling) in both the top and bottom.

  5. Show that you are multipling by the conjugate (on the top and bottom).

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8.

To rationalize \LARGE \frac{-2}{-8+\sqrt{6}}

Which step is correct?

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9.

Rationalize: \LARGE \frac{-2}{-8+\sqrt{6}}

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10.

Rationalize: \LARGE \frac{-1}{-2-\sqrt{7}}

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11.

Rationalize: \LARGE \frac{6}{-8-\sqrt{11}}

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12.

Rationalize: \LARGE \frac{-2}{-4+\sqrt{14}}

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13.

Choose all that are true