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Q: Is the square root of 21 a rational number?

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Rational.

Any number that is presented as an integer "over" (aka divided by) an integer is automatically a rational number - that's what the definition of a rational number is.

Some are and some are not. For example, the square roots of 2.25, 3.61, 4, 4.84, 5.29, 6.76, 7.29, 8.41, 9, 10.89, 11.56, 12.25, 13.69, 14.44, 15.21, 16, 17.64, 18.49, 19.36, 20.25, 21.16, 22.09, 23.04, 24.5025, and 25 are all rational numbers. But the square roots of 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, and 24 are irrational numbers. We believe, but can't prove easily, that there are more irrational square roots than rational ones.

Yes because it can be expressed as a fraction in the form of 21/2

You wont be able to add a rational number and an irrational number and get a number not in a fraction ( 3 + 22/7) (21/7 + 22/7 = 43/7) So, yes as you see in the example above it made another irrational number.

Related questions

Yes because 21 is a rational number

No because it is 2 times the square root of 21 which is an irrational numberThe square root of 84 is not a rational number

irrational

No, they are not.

It is equal to 21/2 which is a rational number

irrational, it has a never ending decimal

First note that 84=4x21 and 4 is a perfect square. So square root of (84)=square root (4x21)=Square root (4) Square root (21)= 2 multiplied by the square root of 21. You can also write this using rational exponents, but this is not in radical form. It is an equivalent expression, however. 2 x (21)1/2

The square roots of 21 are 4.5826 (rounded) and the negative of the same number.

21 is a rational number.

The square root of -21 is: 4.582576 i

The square root of 21 is 4.58257569495584.

The square root of 21 is 4.58257569495584.

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