Gujarat Board GSEB Textbook Solutions Class 7 Maths Chapter 1 Integers Ex 1.2 Textbook Questions and Answers.
Gujarat Board Textbook Solutions Class 7 Maths Chapter 1 Integers Ex 1.2
Question 1.
Write down a pair of integers whose:
(a) sum is – 7
(b) difference is – 10
(c) sum is O
Solution:
(a) We can have (- 2) + (- 5) = – 7
∴ – 2 and – 5 can be a required pair.
(b) We can have – 15 – (- 5) = – 15 + 5 = – 10
∴ – 15 and – 5 can be a required pair.
(c) We can have – 15 + 15 = 0
∴ – 15 and 15 can be a required pair.
Question 2.
(a) Write a pair of negative integers whose difference gives 8.
(b) Write a negative integer and a positive integer whose sum is – 5.
(c) Write a negative integer and a positive integer whose difference is – 3.
Solution:
(a) Since, (- 2) – (- 10) = – 2 + 10 = 8
So, (- 2) and (- 10) is a pair of negative integers such that their difference is 8.
(b) Since, (- 6) + 1 = – 5
Therefore, – 6 and 1 is a pair of integers such that their sum is – 5 and one of them is a negative integer.
(c) Since (- 1) – (2) = -1 – 2 = – 3
Therefore, – 1 and 2 is a pair of integers such that their difference is – 3 and one of them is positive and other is negative.
Question 3.
In a quiz, team A scored – 40, 10, 0 and team B scored 10, 0, – 40 in three successive rounds. Which team scored morel Can we say that we can add integers in any order?
Solution:
Total score of team A = (- 40) + 10 + 0
= – 40 + 10 = – 30
Total score of team B = 10 + 0 + (- 40)
= 10 + (- 40) = – 30
Therefore, scores of both the teams are same, i.e. – 30.
Yes, we can add integers in any order.
Question 4.
Fill in the blanks to make the following statements true:
(i) (- 5) + (- 8) = (- 8) + ( …………. )
(ii) – 53 + …………. = – 53
(iii) 17 + …………. = 0
(iv) [13 + (- 12)] + ( …………. ) = 13 + [(- 12) + (- 7)]
(v) (- 4) + [15 + (- 3)] = [- 4 + 15] + ………….
Solution:
(i) Since, integers can be added in any order,
∴ (- 5) + (- 8) = (- 8) + (- 5)
(ii) If we add zero to any integer, we get the same integer.
∴ 53 + 0 = – 53
(iii) We know that the sum of an integer and its additive inverse is zero.
∴ 17 + (- 17) = 0
(iv) Since, the addition of integers is associative. Therefore, for three integers a, b and c, we have: (a + b) + c = a + (b + c)
Thus, [13 + (- 12)] + ( – 7)
= 13 + [(- 12) + (- 7)]
(v) (- 4) + [15 + (- 3)] = [(- 4) + 15] + (- 3)