ML Aggarwal Rational and Irrational Number Exe-1.2 Class 8 ICSE Maths Solutions. We Provide Step by Step Answer of Exe-1.2 Questions for Rational and Irrational Number as council prescribe guideline for upcoming board exam. Visit official Website CISCE for detail information about ICSE Board Class-8.
ML Aggarwal Rational and Irrational Number Exe-1.2 Class 8 ICSE Maths Solutions
| Board | ICSE |
| Publications | Avichal Publishig Company (APC) |
| Subject | Maths |
| Class | 8th |
| Chapter-1 | Rational and Irrational |
| Writer | ML Aggarwal |
| Book Name | Understanding |
| Topics | Solution of Exe-1.2 Questions |
| Edition | 2023-2024 |
Rational and Irrational Number Exe-1.2
ML Aggarwal Class 8 ICSE Maths Solutions
Page-9
Question 1. Subtract:
(i) 2(3/5) from – 3 / 7
(ii) – 4 / 9 from 3(5/8)
(iii) -3(1/5) from -4(7/9)
Answer :
(i) 2(3/5) from – 3 / 7
= – 3 / 7 – (13 / 5)
Taking the L.C.M., we get,
= (- 15 – 91) / 35
= – 106 / 35
= -3(1/35)
(ii) – 4 / 9 from 3(5/8)
This can be written as,
– 4 / 9 from 29 / 8
= 29 / 8 – (- 4 / 9)
= 29 / 8 + 4 / 9
Taking the L.C.M., we get,
= (261 + 32) / 72
= 293 / 72
= 4(5/72)
(iii) -3(1/5) from -4(7/9)
This can be written as,
= – 16 / 5 from – 43 / 9
= – 43 / 9 – (- 16 / 5)
= – 43 / 9 + 16 / 5
Taking the L.C.M., we get,
= (- 215 + 144) / 45
= – 71 / 45
= -1(26/45)
Question 2. Sum of two rational numbers is 3/5. If one of them is -2/7, find the other.
Answer :
Sum of two rational numbers is 3 / 5
One of the numbers is – 2 / 7
Hence, the other number is calculated as follows:
Other number = 3 / 5 – (- 2 / 7)
= 3 / 5 + 2 / 7
Taking the L.C.M., we get,
= (21 + 10) / 35
= 31 / 35
Hence, the other number is 31 / 35.
Question 3. What rational number should be added to – 5 / 11 to get – 7 / 8?
Answer :
According to the question
Sum of two numbers = – 7 / 8
One number = – 5 / 11
Hence, the other number is calculated as below:
Other number = – 7 / 8 – (- 5 / 11)
= – 7 / 8 + 5 / 11
Taking the L.C.M., we get,
= (- 77 + 40) / 88
= – 37 / 88
Hence, the other number is – 37 / 88.
Question 4. What rational number should be subtracted from -4(3/5) to get -3(1/2) ?
Answer :
The required number can be calculated :
-4(3/5) -3(1/2)
This can be written as,
(- 23 / 5) + (7 / 2)
On further calculation, we get
= (- 46 + 35) / 10
= – 11 / 10
= -1(1/10)
Question 5. Subtract the sum of -5/7 and -8/3 from the sum of 5/2 and -11/12.
Answer :
Sum of – 5 / 7 and – 8 / 3 s,
– 5 / 7 and – 8 / 3 = (- 5 / 7) + (- 8 / 3)
On further calculation,
= (- 15 – 56) / 21
= – 71 / 21
Sum of 5 / 2 and – 11 / 12 can be calculated as,
5 / 2 + (- 11 / 12) = 5 / 2 – 11 / 12
= (30 – 11) / 12
= 19 / 12
19 / 12 – (- 71 / 21)
= 19 / 12 + 71 / 21
Taking the L.C.M.,
= (133 + 284) / 84
= 417 / 84
= 4(81/84)
Question 6. If x = – 4 / 7 and y = 2 / 5, then verify that
(i) x – y ≠ y – x
(ii) -(x+y) = (-x) + (-y)
Answer :
(i) x – y ≠ y – x
x = – 4 / 7 and y = 2 / 5
x – y = – 4 / 7 – (2 / 5)
= – 4 / 7 – 2 / 5
Taking the L.C.M., we get,
= (- 20 – 14) / 35
= – 34 / 35
y – x = 2 / 5 – (- 4 / 7)
= 2 / 5 + 4 / 7
Taking the L.C.M., we get,
= (14 + 20) / 35
= 34 / 35
Hence, x – y ≠ y – x
Question 7. If x = 4 / 9, y = – 7 / 12 and z = – 2 / 3, then verify that x – (y – z) ≠ (x – y) – z
Answer :
x = 4 / 9, y = – 7 / 12, z = – 2 / 3
x – (y – z) ≠ (x – y) – z
L.H.S. = x – (y – z)
= 4 / 9 – {- 7 / 12 – (- 2 / 3)}
= 4 / 9 – (- 7 / 12 + 2 / 3)
= 4 / 9 – {(- 7 + 8) / 12}
= 4 / 9 – (1 / 12)
= 4 / 9 – 1 / 12
Taking the L.C.M.
= (16 – 3) / 36
= 13 / 36
R.H.S = (x – y) – z
= {4 / 9 – (- 7 / 12)} – (- 7 / 12)
= (4 / 9 + 7 / 12) + 7 / 12
On further calculation,
= {(16 + 21) / 36} + 7 / 12
= 37 / 36 + 7 / 12
Again taking the L.C.M.,
= (37 + 21) / 36
= 58 / 36
Hence, x – (y – z) ≠ (x – y) – z
Question 8. Which of the following statement is true/false?
(i) 2 / 3 – 4 / 5 is not a rational number.
(ii) – 5 / 7 is the additive inverse of 5 / 7.
(iii) 0 is the additive inverse of its own.
(iv) Commutative property holds for the subtraction of rational numbers.
(v) Associative property does not hold for the subtraction of rational numbers.
(vi) 0 is the identity element for the subtraction of rational numbers.
Answer :
(i) 2 / 3 – 4 / 5
Taking L.C.M
= (10 – 12) / 15
= – 2 / 15
Is a rational number
Hence, the given statement is false.
(ii) The given statement is true.
(iii) The given statement is true.
(iv) Let us take,
5 / 4 – 3 / 4 = 2 / 4
3 / 4 – 5 / 4 = – 2 / 4
2 / 4 ≠ – 2 / 4
Hence, the given statement is false.
(v) The given statement is true.
(vi) Let us take,
7 / 8 – 0 = 7 / 8
0 – 7 / 8 = – 7 / 8
7 / 8 ≠ – 7 / 8
Hence, the given statement is false.
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