Page 17 - SM inner class 8.cdr

E xercise 1.3

1. Represent these rational numbers on number line:
3 -2 5
(i) (ii) (iii)
5 3 7
2. Find two ratio nal numbers between.
2 3 6 9 1 4 -1 1
(i) and (ii) and (iii) and (iv) and
7 5 5 11 3 5 6 3
3. Find three ratio nal numbers between.
1 1 7 2 -1 3 1 1
(i) and (ii) and (iii) and (iv) and
4 2 10 3 3 2 8 12

Summary
p
m Rational number is said to be in standard form if q is positive and the integers p and q have no common
q
divisor other than 1.

m Any number on number line is greater than any other number lying to the left of it and vice-versa
m When denominator are same, smaller the numerator smaller will be the rational number and
vice-versa.
m Rational numbers are closed under the operations of addition, subtraction and multiplication.
m The operations addition and multiplications are:
(i) Commutative for rational numbers.
(ii) Associative for rational numbers.
m ‘0’ is the additive identity for rational number.
m ‘1’ is the multiplicative identity for rational number.

m A rational number and its additive inverse are opposite in their sign.
m The multiplicative inverse of a rational number is its reciprocal.
m Distributivity of rational numbers a,b and c,
a ( b + c ) = ab + ac and a ( b – c ) = ab – ac
m Rational numbers can be represented on a number line.
m There are infinite rational numbers between two rational numbers.

Review Exercise
1. Give a rational number which when added to it gives the same number.
22 11
2. By what ratio nal number should we divide , so as to get the number -
7 24
3 8 1 7 8
3. Repre sent the follow ing ratio nal numbers on the number line.(i) - (ii) (iii) (iv) (v) -
7 7 3 2 3
1 1 1
4. If you subtract from a number and multi ply the result by , you get . What is the number?
2 2 8
5. Find two ratio nal numbers between (i) -2 and 2. (ii) -1 and 0.
1 2 1 1
6. Insert six ratio nal numbers between (i) - and - (ii) and
3 3 4 2

17
Mathematics In Focus - 8