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7.4B Square Formula and Powers with Radicals

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<strong>7.4B</strong> <strong>Square</strong> <strong>Formula</strong> <strong>and</strong> <strong>Powers</strong> <strong>with</strong> <strong>Radicals</strong><br />

A. <strong>Square</strong> <strong>Formula</strong><br />

Recall the square formula:<br />

<strong>Square</strong> formula:<br />

¡¢<br />

¡£<br />

<strong>Square</strong> the first term ¤¥<br />

Product times two ¦¥<br />

§¥ <strong>Square</strong> the last term<br />

After applying the square formula <strong>with</strong> radicals, remember to simplify.<br />

B. Examples<br />

Example 1: Simplify ¨©� � © §�� .<br />

Solution<br />

Apply the square formula:<br />

� � ¦ § � § ©�©<br />

� § ¤�<br />

� � ¦ ©<br />

Thus we get<br />

Ans � � �© ¦<br />

� ¦ © ¤� �<br />

� ¦ © � �¦ �<br />

1


Example 2: Simplify ¨© ¦ � § � ¡�� .<br />

Solution<br />

By the square formula, we have<br />

¨ ¦ � §�� ¤¢ © ¦ � § � ¦¡<br />

Combining like terms, we have<br />

Ans ¦ � ¦� � ¤¢ © ¦ � §<br />

Example 3: Simplify ¨© � £ � © ¤ � ¦ �� .<br />

Solution<br />

By the square formula, we have<br />

Combining like terms, we have<br />

¨ � £� � ¦ © � £ © ¤ � ¦ � ¨ ¤ ¦ � �<br />

Ans ¡ � � ¦ © � £ © ¤ � ¦ OR ¡ � � ¦¤ ¨ � £� ¨ ¤ � ¦ �<br />

2


Example 4: Simplify ¨ © � ¤� © � ¤�� .<br />

Solution<br />

C. <strong>Powers</strong><br />

By the square formula, we have<br />

¨ © � ¤�� � ¦ © � ¤ © � ¤� ¨ � ¤�<br />

Bringing the power to the inside <strong>and</strong> rearranging, we have<br />

Ans ¤ ¨ � ¤�� � ¦ © � ¤ © � ¤� � ¤<br />

Recall that we use the square formula repeatedly <strong>with</strong> FOIL/factor table.<br />

Example 1: Simplify ¨© � § � © � §�¡ .<br />

Solution<br />

¨© � § © � � §�¡ ¢ ¨© � § © � � §��¨© � § © � � §�<br />

Now apply the square formula:<br />

£ ¨ � §� � ¦ © � § © � §� ¨ � §�¤ ¨© � § � © � §�<br />

Combining like terms:<br />

¨ ¦ � ¦ © � § � © §�¨© � § © � � §�<br />

Now use FOIL to get the answer:<br />

Ans ¦ © � § � ¦ © � § � ¦ ¨ � §� © � § � ¦ ¨ � §� © � §<br />

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Example 2: Simplify ¨ © � ¦� © ¦ � ¤�¡ .<br />

Solution<br />

© ¨ � ¦ � © ¦ � ¤�¡ ¢ © ¨ � ¦� © ¦ � ¤�� © ¨ � ¦� © ¦ � ¤�<br />

Now apply the square formula:<br />

£ ¨ © � ¦�� � ¦ ¨ © � ¦� ¨ © ¦ � ¤�� ¨ © ¦ � ¤��¤ ¨ © � ¦� © ¦ � ¤�<br />

Use the factor table:<br />

© ¨ � ¦�� ¦ © ¨ � ¦� © ¨ ¦ � ¤� © ¨ ¦ � ¤��<br />

© � ¦ � ¦ ¦ © ¨ � ¦�� © ¨ ¦ � ¤� © ¨ � ¦� © ¨ ¦ � ¤��<br />

� © ¦ � ¤ ¨ © � ¦�� ¨ © ¦ � ¤� ¦ ¨ © � ¦� ¨ © ¦ � ¤�� ¦ � ¤<br />

Thus we have<br />

Ans § � ¤� § ¨ © � ¦�� ¨ © ¦ � ¤�� § ¨ © � ¦� ¨ © ¦ � ¤��<br />

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