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Mathematics

Name the multiplication property of rational numbers shown below:

(i) 35×89=89×35\dfrac{3}{5} \times \dfrac{-8}{9} = \dfrac{-8}{9} \times \dfrac{3}{5}

(ii) 34×(57×815)=(34×57)×815\dfrac{-3}{4} \times \Big(\dfrac{5}{7} \times \dfrac{-8}{15}\Big) = \Big(\dfrac{-3}{4} \times \dfrac{5}{7}\Big) \times \dfrac{-8}{15}

(iii) 45×(38+47)=45×38+45×47\dfrac{4}{5} \times \Big(\dfrac{3}{-8} + \dfrac{-4}{7}\Big) = \dfrac{4}{5} \times \dfrac{3}{-8} + \dfrac{4}{5} \times \dfrac{-4}{7}

(iv) 75×57=1\dfrac{-7}{5} \times \dfrac{5}{-7} = 1

(v) 89×1=1×89=89\dfrac{8}{-9} \times 1 = 1 \times \dfrac{8}{-9} = \dfrac{8}{-9}

Rational Numbers

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Answer

(i) Commutativity property

Reason

If ab\dfrac{a}{b} and cd\dfrac{c}{d} are any two rational numbers, then:

ab×cd=cd×ab\dfrac{a}{b} \times \dfrac{c}{d} = \dfrac{c}{d} \times \dfrac{a}{b}

(ii) Associativity property

Reason

If ab,cd\dfrac{a}{b}, \dfrac{c}{d} and ef\dfrac{e}{f} are any three rational numbers, then:

ab×(cd×ef)=(ab×cd)×ef\dfrac{a}{b} \times \Big(\dfrac{c}{d} \times \dfrac{e}{f}\Big) = \Big(\dfrac{a}{b} \times \dfrac{c}{d}\Big) \times \dfrac{e}{f}

(iii) Distributivity property

Reason

If ab,cd\dfrac{a}{b}, \dfrac{c}{d} and ef\dfrac{e}{f} are any three rational numbers, then:

ab×(cd+ef)=(ab×cd)+(ab×ef)\dfrac{a}{b} \times \Big(\dfrac{c}{d} + \dfrac{e}{f}\Big) = \Big(\dfrac{a}{b} \times \dfrac{c}{d}\Big) + \Big(\dfrac{a}{b} \times \dfrac{e}{f}\Big)

(iv) Existence of inverse

Reason

The multiplicative inverse of ab\dfrac{a}{b} = reciprocal of ab=ba\dfrac{a}{b} = \dfrac{b}{a}.

(v) Existence of identity

Reason

For a rational number ab\dfrac{a}{b},

1×ab=ab×1=ab1 \times \dfrac{a}{b} = \dfrac{a}{b} \times 1 = \dfrac{a}{b}.

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