Ncert Class 8 Maths Chapter 1 exercise 1.1
NCERT solutions for class 8 maths| Chapter 1 Rational numbers
A detailed and step-wise solutions to all the questions at the end of the chapter from the NCERT Maths book are given below:
1. Using appropriate properties find
Sol. (by commutativity)
2. Write the additive inverse of each of the following:
3. Verify that for (i)
Sol. (i) We have
The additive inverse of is
The same equality
(ii) We have ,
The additive inverse of
The same equality , shows that the additive inverse of
4. Find the multiplicative inverse of the following.
(i) – 13
Sol. We say that a rational number is called the reciprocal or multiplicative inverse of another non-zero rational number
Sol. Since , so multiplicative inverse of –
Sol. Multiplicative inverse of is 5 , because
Since ,so multiplicative inverse of
(vi) – 1
Sol. Multiplicative inverse of -1 is -1 , because (-1) x (-1) =1 .
5. Name the property under multiplication used in each of the following
Sol. 1 is the multiplicative identity.
Sol. Commutativity of rational numbers.
Sol. Multiplicative inverse .
Sol. The reciprocal of
Now the product of and
7. Tell what property allows you to compute
Sol. Associativity of rational numbers.
9. Is 0.3 the multiplicative inverse of
Sol. Yes, 0.3 is the multiplicative inverse of because
(i) The rational number that does not have a reciprocal. Ans. 0
(ii) The rational numbers that are equal to their reciprocals. Ans. 1 and -1
(iii) The rational number that is equal to its negative. Ans. 0
11. Fill in the blanks.
(i) Zero has ____no____ reciprocal.
(ii) The numbers ___1_____ and __-1______ are their own reciprocals
(iii) The reciprocal of – 5 is ________.
(iv) Reciprocal of
(v) The product of two rational numbers is always a ____rational number___.
(vi) The reciprocal of a positive rational number is __positive______.
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