NCERT Solutions Class 7th Maths Chapter – 1 Integers Exercise – 1.1

1. Write a pair of integers such that

(a) sum is -7

Solution: Take a pair of integers –6 and –1
= (-6) + (-1)
= -6 – 1
= -7

(b) The difference is -10

Solution: Take a pair of integers –14 and –4
= (-14) – (-4)
= -14 + 4
= -10

(c) The sum should be 0.

Solution: Took a pair of integers –5 and 5
= (-5) + (5)
= -5 + 5
= 0

2. (a) Write a pair of negative integers whose difference is 8.

Solution: The difference should be 8, Take such a pair -3 and -11
= (-3) – (-11)
= -3 + 11
= 8

(b) Write one negative integer and one positive integer whose sum is -5.

Solution: We took the pair –9 and 4
= (-9) + (4)
= –9 + 4
= –5

(c) Write a negative integer and a positive integer whose difference is –3.

Solution: The difference is -3, Such a pair is taken -2 and 1
= (-2) – (1)
= – 2 – 1
= -3

3. In three consecutive rounds of a quiz, the marks scored by Team A were – 40, 10, 0 and the marks scored by Team B were 10, 0, – 40. Which team scored more points? Can we say that integers can be added in any order?

Solution:

Total score of Team A
= (- 40) + (10) + (0)
= – 40 + 10 + 0
= – 30

Total score of Team B
= 10 + 0 + (- 40)
= 10 + 0 – 40
= – 30

Hence both teams have the same score i.e. -30
Yes, we can add the integers in any order.

4. Fill in the blanks to make the following statements true:

(i) (-5) + (-8) = (-8) + (…)

Solution: -5 + (-8) = (-8) + (-5) [Consecutive Law of Addition]

(ii) -53 + … = -53

Solution: -53 + 0 = -53 [Additive Identity]
[Adding 0 to any integer gives the same value]

(iii) 17 + … = 0

Solution: 17 + (-17) = 0 [Additive inverse]

(iv) [13 + (-12)] + (…) = 13 + [(-12) + (-7)]

Solution: [13 + (-12)] + (-7) = 13 + [(-12) + (-7)] [Associative Law of Addition]

(v) (-4) + [15 + (-3)] = [ -4 + 15] + …

Solution: (-4) + [15 + (-3)] = [-4 + 15] + (-3) [Associative Law of Addition]