physicscatalyst.com logo





NCERT Solutions for Class 8 maths Chapter 1 Rational Numbers Exercise 1.1




In this page we have NCERT Solutions for Class 8 maths Chapter 1 Rational Numbers for Exercise 1.1. This Exercise has questions on Properties of Rational nnumber, Additive inverse, Multiplicative inverse, additive identity. Hope you like them and do not forget to like , social share and comment at the end of the page.

NCERT Solutions for Class 8 maths Chapter 1 Exercise 1.1

Question 1:
Using appropriate properties find:
NCERT Solutions for Class 8 maths Chapter 1 : rational Numbers

Answer
(i)Using commutativity property of rational number Ncert Solutions for rational Numbers Class 8 Exercise 1.1
Now using Distributivity property
Ncert Solutions for rational Numbers Class 8 Exercise 1.1
Ncert Solutions for rational Numbers Class 8 Exercise 1.1
(ii) Using commutativity property of rational numbers
Ncert Solutions for rational Numbers Class 8 Exercise 1.1
Now using Distributivity property
Ncert Solutions for rational Numbers Class 8 Exercise 1.1

Question 2
Write the additive inverse of each of the following:
(a) $\frac {2}{8}$
(b) $ \frac {-5}{9}$
(c) $\frac {-6}{-5}$
(d) $\frac {2}{-9}$
(e) $\frac {19}{-6}$

Answer:
(i) $\frac {2}{8}$
Additive inverse of $\frac {2}{8}$= $\frac {-2}{8}$
(ii) $ \frac {-5}{9}$

Additive inverse of $ \frac {-5}{9}$ = $ \frac {5}{9}$
(iii) $\frac {-6}{-5} =\frac {6}{5}$

Additive inverse of $\frac {-6}{-5}$= $\frac {-6}{5}$
(iv)$\frac {2}{-9}=\frac {-2}{9}$

Additive inverse of $\frac {2}{-9}$ =$\frac {2}{9}$
(v) $\frac {19}{-6}= \frac {-19}{6}$

Additive inverse of $\frac {19}{-6}$ =$\frac {19}{6}$


Question 3
Verify that - ( - x) = x for.
(i) x =11/15 (ii) x=-13/17
Answer:
(i) x=11/15 Additive inverse
-x=-11/15 As (11/15) + (-11/15) =0
The above also represent that additive inverse of (-11/15) is (11/15) or we can say that
-(-11/15)=11/15
Or x=-(-x)
(ii) x=-13/17
Additive inverse
-x=-13/17 As (-13/17) + (13/17) =0
The above also represent that additive inverse of (13/17) is (-13/17)) or we can say that
-(13/17) = -13/17
Or x=-(-x)

Question 4
Find the multiplicative inverse of the following.
(a)$-13$
(b)$ \frac {-13}{19}$
(c) $\frac {1}{5}$
(d) $\frac {-5}{8} \times \frac {-3}{7}$
(e) $-1 \times \frac {-2}{5}$
(f) $-1$

Answer
(a) $-13$
Multiplicative inverse of $-13$=$\frac {-1}{13}$

(b)$ \frac {-13}{19}$
Multiplicative inverse of $ \frac {-13}{19}$ =$ \frac {-19}{13}$

(c)$\frac {1}{5}$
Multiplicative inverse of $\frac {1}{5}$=$5$

(d) $\frac {-5}{8} \times \frac {-3}{7}=\frac {15}{56}$
Multiplicative inverse of $\frac {-5}{8} \times \frac {-3}{7}$ =$\frac {56}{15}$

(e) $-1 \times \frac {-2}{5}= \frac {2}{5}$
Multiplicative inverse of $-1 \times \frac {-2}{5}$ =$ \frac {5}{2}$

(f) $-1$<
Multiplicative inverse of $-1$=-1


Question 5 :
Name the property under multiplication used in each of the following:
NCERT Solutions for Class 8 maths Chapter 1 : rational Numbers Question 5
Answer:
  1. 1 is the multiplicative identity
  2. Commutatively
  3. Multiplicative inverse

Question 6:
Multiply 6/13 by the reciprocal of -7/16
Answer
Reciprocal of -7/16= -16/7
So $ \frac {6}{13} \times (- \frac {16}{7}) =- \frac {96}{91}$

Question 7 Tell what property allows you to compute
Ex 1.1 Class 8 Question 6
Answer:
Associativity


Question 8
Is 8/9 the multiplicative inverse of $-1 \frac {1}{8}$
Why or why not?
Answer:
$-1 \frac {1}{8}$
$=\frac {-9}{8}$
Now
$ \frac {8}{9} \times (-\frac {9}{8}) = -1$
So it is not the multiplicative inverse

Question 9 Is 0.3 the multiplicative inverse of $3 \frac {1}{3}$
Why or why not?
Answer:
$3 \frac {1}{3}$
=10/3
Now
$ \frac {3}{10} \times \frac {10}{3} =1$
So it is the multiplicative inverse

Question 10
Write:
(i) The rational number that does not have a reciprocal.
(ii) The rational numbers that are equal to their reciprocals.
(iii) The rational number that is equal to its negative.

Answer:
  1. 0
  2. 1 and -1
  3. 0
Question 11 :
Fill in the blanks.
(i) Zero has __________ reciprocal.
(ii) The numbers __________ and __________ are their own reciprocals
(iii) The reciprocal of - 5 is __________.
(iv) Reciprocal of (1/x) where is x ≠ 0 __________.
(v) The product of two rational numbers is always a __________.
(vi) The reciprocal of a positive rational number is __________.

Answer:
  1. No
  2. 1 and -1
  3. -1/5
  4. X
  5. Rational Number
  6. Positive rational number

Summary

  1. NCERT Solutions for Class 8 maths Chapter 1 Rational Numbers Exercise 1.1 has been prepared by Expert with utmost care. If you find any mistake.Please do provide feedback on mail. You can download the solutions as PDF in the below Link also
    Download Rational numbers Class8 Exercise 1.1 as pdf
  2. This chapter 1 has total 2 Exercise 1.1 and 1.2. This is the first exercise in the chapter.You can explore previous exercise of this chapter by clicking the link below

Also Read




Class 8 Maths Class 8 Science


Latest Updates
Synthetic Fibres and Plastics Class 8 Practice questions

Class 8 science chapter 5 extra questions and Answers

Mass Calculator

3 Fraction calculator

Garbage in Garbage out Extra Questions7