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Which expression results in a rational number? (1) 121 - 121 (3) 36 + 225 (2) root 25 . 50 (4) 315 + 2,5

User Obey
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1 Answer

20 votes
20 votes

We will have the following:

*First: We test the expressions:

1)


\sqrt[]{121}-\sqrt[]{21}=11-\sqrt[]{21}

2)


\sqrt[]{21}\cdot\sqrt[]{50}=5\sqrt[]{42}

3)


\sqrt[]{36}+\sqrt[]{225}=21

4)


3\sqrt[]{5}+2\sqrt[]{5}=5\sqrt[]{5}

So, the only rational number would be in option 3:


21=(21)/(1)

User Neil From Ohio
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