## Wednesday 5 October 2011

### CBSE Class VII (7th) Mathematics Chapter 1 Integers : Exercise 1.2

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

(a) 3+(−10) = −7
(b) −4−(−6) = −10
(c) −7 + 7= 0

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.
(a)  −5−(−13) = 8
(b) −8 + 3 = −5
(c) −2 − (+ 1) = −3

3. 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?
Total score of team A in three successive rounds = – 40 +10 + 0 = –30
Total score of team B in three successive rounds = 10+ 0+( – 40) = –30
Both the team score have equal score
Yes, we can add integers in any order. As we have seen above,  the scores of  both teams in successive rounds were numerically same but different in order. Yet, after addition,  the total score of both teams were equal.

4. 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] +......

(i) (− 5) + (− 8) = (− 8) + (-5)
(ii) − 53 + 0 = − 53
(iii) 17 + −17 = 0
(iv)[ 13 + (− 12)] + (−7) = 13 + [(− 12) + (− 7)]
(v) (− 4) + [15 + (− 3)] = [(− 4) + 15] +(−3 )
CBSE Class VII (7th) Mathematics Chapter 1 Integers : Exercise 1.2

1. 2. 