We are asked whether the following is rational or irrational?
Let us have a look at what are rational and irrational numbers?
Rational number:
These numbers can be written as a simple fraction.
Example:
1/5, 2/3, 1/10
Irrational numbers:
These numbers cannot be written as a simple fraction.
Example:
π = 3.14159 …
As you can see the decimal numbers are keep on repeating but they are different,
√2 = 1.414213 …
The number 70 is under the square root.
Whenever we have a number under the square root then we have to check if it is a perfect square or not.
Example of perfect square:
√36 = 6
√64 = 8
√100 = 10
If it is a perfect square then the square root of that number will be rational.
If it is not a perfect square then the square root of that number will be irrational.
Since 70 is not a perfect square, therefore, √70 is irrational.