Associative Property Of Rational Numbers With Examples

The definition and explanation with examples of the Associative property of rational numbers.

Associative Property Of Rational Numbers

If we take the three rational numbers -3/4, 2/3 and 2 1/2, for example, then we have;

addition;

$\displaystyle \frac{-3}{4}+\left( \frac{2}{3}+2\frac{1}{2} \right)=\frac{-3}{4}+\left( \frac{4}{6}+2\frac{3}{6} \right)=\frac{-3}{4}+2\frac{7}{6}=\frac{-9}{12}+2\frac{14}{12}=2\frac{5}{12}$

=

$\displaystyle \left( \frac{-3}{4}+\frac{2}{3} \right)+2\frac{1}{2}=\left( \frac{-9}{12}+\frac{8}{12} \right)+2\frac{1}{2}=\frac{-1}{12}+2\frac{1}{2}=\frac{-1}{12}+2\frac{6}{12}=2\frac{5}{12}$

RESULTS ARE EQUAL TO EACH OTHER

In general if a/b, c/d, e/f ∈ Q then;

$\displaystyle \frac{a}{b}+\left( \frac{c}{d}+\frac{e}{f} \right)=\left( \frac{a}{b}+\frac{c}{d} \right)+\frac{e}{f}$

The set of rational numbers is associative under addition.

subtraction;

$\displaystyle \frac{-3}{4}-\left( \frac{2}{3}-2\frac{1}{2} \right)=\frac{-3}{4}-\left( \frac{4}{6}-2\frac{3}{6} \right)=\frac{-3}{4}-\left( \frac{4}{6}+-1\frac{9}{6} \right)=\frac{-3}{4}-\left( -1\frac{5}{6} \right)=\frac{-9}{12}+\left( +1\frac{10}{12} \right)=1\frac{1}{12}$

≠

$\displaystyle \left( \frac{-3}{4}-\frac{2}{3} \right)-2\frac{1}{2}=\left( \frac{-9}{12}+\frac{-8}{12} \right)-2\frac{1}{2}=\frac{-17}{12}-2\frac{1}{2}=-1\frac{-5}{12}-2\frac{6}{12}=-3\frac{11}{12}$

RESULTS ARE NOT EQUAL TO EACH OTHER

In general if a/b, c/d, e/f ∈ Q then;

$\displaystyle \frac{a}{b}-\left( \frac{c}{d}-\frac{e}{f} \right)\ne \left( \frac{a}{b}-\frac{c}{d} \right)-\frac{e}{f}$

The set of rational numbers is not associative under subtraction.

multiplication;

$\displaystyle \frac{-3}{4}x\left( \frac{2}{3}x2\frac{1}{2} \right)=\frac{-3}{4}x\left( \frac{2}{3}x\frac{5}{2} \right)=\frac{-3}{4}x\frac{5}{3}=\frac{-5}{4}=-1\frac{1}{4}$

=

$\displaystyle \left( \frac{-3}{4}x\frac{2}{3} \right)x2\frac{1}{2}=\left( \frac{-1}{2}x2\frac{1}{2} \right)=\frac{-1}{2}x\frac{5}{2}=\frac{-5}{4}=-1\frac{1}{4}$

RESULTS ARE EQUAL TO EACH OTHER

In general if a/b, c/d, e/f ∈ Q then;

$\displaystyle \frac{a}{b}x\left( \frac{c}{d}x\frac{e}{f} \right)=\left( \frac{a}{b}x\frac{c}{d} \right)x\frac{e}{f}$

The set of rational numbers is associative under multiplication.

division;

$\displaystyle \frac{-3}{4}\div \left( \frac{2}{3}\div 2\frac{1}{2} \right)=\frac{-3}{4}\div \left( \frac{2}{3}x\frac{2}{5} \right)=\frac{-3}{4}\div \frac{4}{15}=\frac{-3}{4}x\frac{15}{4}=-\frac{45}{16}=-2\frac{13}{16}$

≠

$\displaystyle \left( \frac{-3}{4}\div \frac{2}{3} \right)\div 2\frac{1}{2}=\left( \frac{-3}{4}x\frac{3}{2} \right)\div 2\frac{1}{2}=\frac{-9}{8}\div 2\frac{2}{5}=\frac{-9}{8}x\frac{2}{5}=-\frac{9}{20}$