Samacheer Kalvi 8th Maths Solutions Term 1 Chapter 1 Rational Numbers Ex 1.3

Samacheer Kalvi 8th Maths Solutions Term 1 Chapter 1 Rational Numbers Ex 1.3

Tamilnadu Samacheer Kalvi 8th Maths Solutions Term 1 Chapter 1 Rational Numbers Ex 1.3

Question 1.
Match the following appropriately.

Solution:
(i) 5
(ii) 4
(iii) 2
(iv) 3
(v) 1

Question 2.
Which of the following properties hold for subtraction of rational numbers? Why?
(a) closure
(b) commutative
(c) associative
(d) identity
(e) inverse

Question 1.
Show that

Solution:

Distance between B and C = 900 km

Question 4.
Give an example for each of the following statements.
(i) The collection of all non-zero rational numbers is closed under division.
(ii) Subtraction is not commutative for rational numbers.
(iii) Division is not associative for rational numbers.
(iv) Distributive of multiplication over subtraction is true for rational numbers, that is a (b – c) = ab – ac.
(v) The mean of two rational numbers is rational and lies between them.

∴ Division is not associative for rational numbers

∴ From (1) and (2)
a × (b – c) = ab – bc
∴ Distributivity of multiplication over subtraction is true for rational numbers.

Question 5.
If 1/4 of a ragi adai weighs 120 grams, 4what will be the weight of 2/3 of the same ragi adai?
Solution:
Let the weight of 1 ragi adai = x grams given 1/4 of x = 120 gm
1/4 × x = 120
x = 120 × 4
x = 480 gm
∴ 2/3 of the adai
= 2/3 × 480 gm = 2 × 160 gm = 320 gm
2/3 of the weight of adai = 320 gm

Question 7.
If p + 2q = 18 and pq = 4o, find 2/p+1/q
Solution:
Given p + 2q = 18 …………… (1)
pq = 40 ………… (2)