RS Aggarwal Class 7 Mathematics First Chapter Integers Exercise 1A Solution
EXERCISE 1A
(1) Evaluate:
(i) 15 + (- 8)
= 15 – 8
= 7
(ii) (- 16) + 9
= – 16 + 9
= – 7
(iii) (- 7) + (- 23)
= – 7 – 23
= – 30
(iv) (- 32) + 47
= – 32 + 47
= 15
(v) 53 + (- 26)
= 53 – 26
= 27
(vi) (- 48) + (- 36)
= – 48 – 36
= – 84
(2) find the sum of:
(i) 153 and – 302
= 153 + (- 302)
= 153 – 302
= – 149
(ii) 1005 and – 277
= 1005 + (- 277)
= 1005 – 277
= 728
(iii) – 2035 and 297
= – 2035 + 297
= – 1738
(iv) – 489 and – 324
= – 489 + (- 324)
= – 489 – 324
= – 813
(v) – 1000 and 438
= – 1000 + 438
= – 562
(vi) – 238 and 500
= – 238 + 500
= 262
(3) Find the additive inverse of:
(i) – 83
= 83
(ii) 256
= – 256
(iii) 0
= 0
(iv) – 2001
= 2001
(4) Subtract:
(i) 28 from – 42
= – 42 – 28
= – 70
(ii) – 36 from 42
= 42 – (- 36)
= 42 + 36
= 78
(iii) – 37 from – 53
= – 53 – (- 37)
= – 53 + 37
= – 16
(iv) – 66 from – 34
= – 34 – (- 66)
= – 34 + 66
= 32
(v) 318 from 0
= 0 – 318
= – 318
(vi) – 153 from – 240
.= – 240 – (- 153)
= – 240 + 153
= – 87
(vii) – 64 from 0
= 0 – (- 64)
= 64
(viii) – 56 from 144
= 144 – (- 56)
= 144 + 56
= 200
(5) Subtract the sum of – 1032 and 878 from – 34.
= – 34 – (- 1032 + 878)
= – 34 – (- 154)
= – 34 + 154
= 120
(6) Subtract – 134 from the sum of 38 and – 87.
= {38 + (- 87)} – (- 134)
= (38 – 87) + 134
= – 45 + 134
= 89
(7) Fill in the banks:
(i) {(- 13) + 27} + (- 41) = (- 13) + {27 + (- 41)}
(ii) (- 26) + {(- 49) + (- 83)} = {(- 26) + (- 49)} + (- 83)
(iii) 53 + (- 37) = (- 37) + (53)
(iv) 9- 68) + (- 76) = 9- 760 + (- 68)
(v) (- 72) + (0) = – 72
(vi) – (- 83) = 83
(vii) (- 60) – (- 1) = – 59
(viii) (- 31) + (- 9) = – 40
(8) Simplify:
{- 13 – (- 27)} + {- 25 – (- 40)}
= {- 13 + 27} + {- 25 + 40}
= 14 + 15
= 29
(9) Find 36 – (- 64) and (- 64) – 36. Are they equal?
∴ 36 – (- 64) = (- 64) – 36
L. H. S. = 36 – (- 64)
= 36 + 64 = 100
R. H. S. = (- 64) – 36
= – 64 -36 = – 100
No, they are not equal.
(10) If a = – 8, b = – 7, c = 6, verify that (a + b) + c = a + (b + c)
R. H. S. = (a + b) + c
= {- 8 + (- 7)} + 6
= – 8 – 7 + 6
= – 15 + 6 = – 9
R. H. S. = a + (b + c)
= – 8 + {(- 7) + 6}
= – 8 – 7 + 6
= – 15 + 6 = – 9 = L. H. S. (proved)
(11) If a = – 9 and b = – 6, show that (a – b) ≠ (b – a)
L. H. S. = (a – b)
= {(- 9) – (-6)}
= – 9 + 6 = – 3
R. H. S. = (b – a)
= {(- 6) – (- 9)}
= – 6 + 9
= 3 ≠ L. H. S. (proved)
(12) The sum of two integers is – 16. If one of them is 53, find the other.
Solution: The required integer is = – 16 – 53 = – 69
(13) The sum of two integers is 65. If one of them is – 31, find the other.
Solution: 65 – 31 = 34, therefore the other is 34.
(14) The difference of an integer a and (- 6) is 4. Find the value of a.
∴ a – (- 6) = 4
Or, a + 6 = 4
Or, a = 4 – 6
Or, a = – 2
(15) Write a pair of integers whose sum gives
(i) zero
Solution: 6 +(- 6) = 6 – 6 = 0
(ii) a negative integer
Solution: 4 + (- 9) = 4 – 9 = – 5
(iii) an integer greater than both the integers
Solution: (- 3) + (- 5) = – 3 – 5 = – 8
(iv) an integer greater than both the integers
Solution: 4 + 5 = 9
(v) an integer smaller than only one of the integers
Solution: 5 + (- 3) = 5 – 3 = 2
(16) For each of the following statements, write (T) for true and (F) for false:
(i) The smallest integer is zero. = F
(ii) – 10 is greater than – 7 = F
(iii) Zero is larger than every negative integer. = T
(iv) The sum of two negative integers is a negative integer. = T
(v) The sum of a negative integer and a positive integer is always a positive integer. = F
For more exercise solutions, Click Below –
Leave a Reply