NCERT Class 8 Solutions: Rational Numbers (Chapter 1) Exercise 1.1 – Part 4

Q-7) Tell what property allows you to compute 13×(6×43)as(13×6)×43

Solution:

By the property of associativity

Image discribing associative property a + ( b + c) = (a + b) + c and a(bc)= (ab)c

Assocuative Property of Additiona Nd Subtraction

Image discribing associative property a + ( b + c) = (a + b) + c and a(bc)= (ab)c

Q-8) Is 89 the multiplicative inverse of 118 ? Why or why not?

Solution:

If it will be the multiplicative inverse then their product will be 1.

inver

Multiplicative inverse of a number as reciprocal

Property of Inverse of a Number Wrt Multiplication

Multiplicative inverse of a number as reciprocal

118=78

Therefore, 89×(78)=791

Hence, 89 is not the multiplicative inverse.

Q-9 Is 0.3 the multiplicative inverse of 313 ? Why or why not?

Solution:

If it will be the multiplicative inverse then their product will be 1.

Multiplicative inverse of fractions as reciprocal

Multiplicative Inverse of Fractions

Multiplicative inverse of fractions as reciprocal

313=103

Also 0.3=310

That is 310×103=1

Hence, 0.3 is the multiplicative inverse.

Q-10 Write

  1. The rational number that does not have a reciprocal.

  2. The rational numbers that is equal to their reciprocals.

  3. The rational number that is equal to its negative.

Solution:

Given the Rational and irrational number in figure and find the related number in questions

Given the Rational and Irrational Number in Figure

Given the Rational and irrational number in figure and find the related number in questions

  1. 0(Zero) is the rational number which does not have a reciprocal.

  2. 1 and -1 are the rational numbers which are equal to their reciprocals

    1=11=1and1=11=1

  3. 0 is the rational number that is equal to its negative

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