CBSE Class 7 Maths - Integers - NCERT Exercise 1.2 (#cbsenotes)

Integers

EXERCISE 1.2

CBSE Class 7 Maths

Q1: 1. Write down a pair of integers whose:
(a) sum is –7
(b) difference is –10
(c) sum is 0

Answer:
(a) One such pair whose sum is -7 = -4 + (-3) = -7
(b) One such pair whose difference is -10 = -3 - 7 = 10
(c) One such pair whose sum is 0 = -5 + 5 = 0




Q2: 
(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.

Answer:

(a)  -2  + (-10) - (3 + 1) = 8
(b)  -7 + 2 = -5
(c)  -1 - (2) = -3


Q3: In a quiz, team A scored – 40, 10, 0 and team B scored 10, 0, – 40 in three successive rounds.  Which team scored more? Can we say that we can add integers in any order?

Answer:
Team A scored  -40, 10, 0
Total score of Team A = -40 + 10 + 0 = -30

Team B scored 10, 0, -40
Total score of Team B = 10 + 0 + (-40) = 10 _ 0 - 40 = -30

Thus, scores of both teams are same.

Yes, we can add integers in any order due to commutative property.

Q4: Fill in the blanks to make the following statements true:
(i) (–5) + (............) = (– 8) + (............)
(ii) –53 + ............ = –53
(iii) 17 + ............ = 0
(iv) [13 + (– 12)] + (............) = ............ + [(–12) + (–7)]
(v) (– 4) + [............ + (–3)] = [............ + 15] + ............

Answer:

(i) (–5) + (–8) = (–8) + (–5) [Commutative Property]
(ii) –53 + 0 = –53 [Zero Additive Property]
(iii) 17 + (–17) = 0 [Additive Identity]
(iv) [13 + (–12)] + (-7) = 13 + [(–12) + (–7)] [Associative Property]
(v) (– 4) + [15 + (–3)] = [ -4 + 15] + (-3) [Associative Property]

MCQs (Q5 - Q 7)

Q5: Sum of two negative number is always
(a) Positive
(b) Negative
(c) 0
(d) 1

Answer: (b) Negative


Q6: The pair of integers whose sum is -5
(a)  1, -4
(b) -1, 6
(c) -3, -2
(d)  5, 0

Answer: (c) -3, -2


Q7: What will be the additive inverse of -5

(a) -6
(b) -4
(c) 3
(d) 5

Answer: (d) 5


Q8: Write the following in ascending order:
1, 0, 2, -3, 4, -7

Answer: -7, -3, 0, 1, 2, 4