# CLASS-8CONCEPT OF RATIONAL NUMBER

RATIONAL NUMBER

If there a fractional number which can be expressed in the form a/b, where a & b are integers whereas a 0 and b 0, so these numbers should be called Rational Number. Suppose the set of rational numbers is denoted by Q

a

So,  Q = { -------- :  a, b I , and b 0 }

b

We can say, obviously Fractions are rational numbers. For example -

5          8         9        -7       -11

------, ------, ------, ------, ------ are rational numbers.

11        35       25       17       115

We have remember that, natural numbers and integers are also rational numbers, as an example –

9               27              -25              -17

9 = -------, 27 = ------, -25 = -------, -17 = -------

1                1                1                 1

Any terminating or recurring decimal can be expressed as a rational number, for example -

3313                   29

3.313 = --------,  0.325 =  --------, etc are rational numbers.

1000                    90

Numbers such as √2, √3 & ∏ cannot be expressed as rational numbers, they are called irrational.