NCERT Solutions for Class 8 Chapter 1 Rational Numbers -Free PDF Download

Free PDF download of NCERT Solutions Maths Class 8 Solutions Chapter 1 – Rational Numbers solved by Expert Maths Teachers on CoolGyan.Org. All Chapter 1 – Rational Numbers Questions with Solutions for NCERT to help you to revise complete Syllabus and Score More marks.

Maths Revision Notes for Class 8

NCERT SOLVED

Questions

1. Using appropriate properties to find:

(i) 

(ii) 

Ans. (i)

= [Using Associative property]

=  [Using distributive property]

= 35(−4−16)+5235(−4−16)+52

= 

= 

=  =  = 2

(ii)

=  [Using Associative property]

=  [Using distributive property]

= 

=  = 

=  = 

2. Write the additive inverse of each of the following:

(i)   (ii)   (iii) (iv) (v)

Ans. We know that additive inverse of a rational number  is  such that 

(i) Additive inverse of  is   (ii) Additive inverse of  is 

(iii) Additive inverse of  is (iv) Additive inverse of  is 

(v) Additive inverse of  is 

3. Verify that  for:

(i)  (ii)

Ans. (i) Putting  in 

L.H.S. = R.H.S.

Hence, verified.

(ii) Putting  in 

L.H.S. = R.H.S.

Hence, verified.

4. Find the multiplicative inverse of the following:

(i)  (ii)  (iii)

(iv)  (v)  (vi)

Ans. We know that multiplicative inverse of a rational number  is  such that 

(i) Multiplicative inverse of  is 

(ii) Multiplicative inverse of  is 

(iii) Multiplicative inverse of  is 

(iv) Multiplicative inverse of  is 

(v) Multiplicative inverse of  is 

(vi) Multiplicative inverse of  is  = -1

5. Name the property under multiplication used in each of the following:

(i)

(ii)

(iii)

Ans. (i) 1 is the multiplicative identity.

(ii) commutativity property.

(iii) Multiplicative Inverse property.

6. Multiply  by the reciprocal of 

Ans. The reciprocal of  is 

According to the question,

 = 

7. Tell what property allows you to compute

 as 

Ans. By using associative property of multiplication,

we will compute as .

8. Is  the multiplicative inverse of  Why or why not?

Ans. Since multiplicative inverse of a rational number  is  if 

Therefore, =  = 

But its product must be positive 1.

Therefore,  is not the multiplicative inverse of 

9. Is 0.3 the multiplicative inverse of  Why or why not?

Ans.  Since multiplicative inverse of a rational number  is  if 

Therefore, =  = 1

Therefore, Yes 0.3 is the multiplicative inverse of 

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.

Ans.(i) 0

(ii) 1 and 

(iii) 0

11. Fill in the blanks:

(i) Zero has ____________ reciprocal.

(ii) The numbers ___________ and __________ are their own reciprocals.

(iii) The reciprocal of  is _____________.

(iv) Reciprocal of  where  is _____________.

(v) The product of two rational numbers is always a ____________.

(vi) The reciprocal of a positive rational number is _______________

Ans. (i) No

(ii) 1, 

(iii) 

(iv) 

(v) Rational Number

(vi) Positive