ML Aggarwal Class 7 Solutions for ICSE Maths Chapter 1 Integers Ex 1.2
Question 1.
Write a pair of integers whose:
(i) sum is -3
(ii) difference is -5
(iii) difference is 4
Solution:
Pair of integers whose,
(i) sum is -3 = -6, 3 (-6 + 3 = -3)
(ii) difference is -5 = -2, 3 (-2 – 3 = -5)
(iii) difference is 4 = -3, -7 [-3 – (-7) = -3 + 7 = 4]
Question 2.
(i) Write a pair of negative integers whose difference is 5.
(ii) Write a negative integer and a positive integer whose sum is -8.
(iii) Write a negative integer and a positive integer whose difference is -3.
Solution:
(i) Let two negative integers whose difference is 5 be -7, -12.
Now the difference is -7 – (-12)
= -7 + 12 = 5
(ii) Let two integers one negative and other positive but sum is -8 are -13, 5
= -13 + 5 = -8
(iii) Let two integer, one negative and other positive whose difference is -3 be -1, 2
Difference = -1 – (2) = -1 – 2 = -3
Question 3.
Write two integers which are smaller than -5 but their difference is greater than -5.
Solution:
Let two integer which are smaller than -5 but their difference is greater than -5
= -6, -8 as -6 – (-8)
= -6 + 8
= 2 > -5
Question 4.
In a quiz, team A scored -30, 20, 0 and team B scored 20, 0, -30 in three successive rounds. Which team socred more? Can we
say that we can add integers in any order?
Solution:
In a quiz,
Team A scored -30, 20, 0 and
Team B scored 20, 0, -30 in three rounds
Sum of scores of A team = -30 + 20 + 0 = -10
Sum of scores of B team = 20 + 0 – 30 = -10
The scores of both the team are equal i.e. -10
Yes, by adding the scores in any order, the result will be the same.
Question 5.
Find the sum of integers -72, 237, 84, 72, -184, -37.
Solution:
Sum of integers -72, 237, 84, 72, -184, -37
= -72 + 237 + 84 + 72 + -184 + -37
= 237 + 84 + 72 + (-72 – 184 – 37)
= (393) + (-293)
= 393 – 293
= 100