Question

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

Answer 1

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)`