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- 64
- êêèDIVIDING FRACTIONS, ELEMENTARY LEVEL
-
- è In this section we will be looking at dividing positive fractions.
- When you divide two positive fractions, the answer is always positive.
- The procedure is to change the operation to multiplication, invert the
- second fraction, then treat the problem as a multiplication problem.
- The positive fractions are described in the list below.
-
- êêêëPositive Fractions
-
- #êêê╚è╔è╩è╦è╠è═è╬ï...
- êêê1è1è1è1è1è1è1
-
- #êêê╚è╔è╩è╦è╠è═è╬ï...
- êêê2è2è2è2è2è2è2
-
- #êêê╚è╔è╩è╦è╠è═è╬ï...
- êêê3è3è3è3è3è3è3
- êêê.
- êêê.
- êêê.
-
- Example 1)èDivide the fractions, 16/5 by 12/15.ïIt is very important
- that the fraction that is doing the dividing is written as the second
- fraction.ïSince 12/15 is doing the dividing, it must be the second
- fraction.ïYou may have noticed a pattern at this point.ïIf you recall,
- it is also important in subtracting fractions which fraction comes
- second.ïIn the addition and multiplication operations, however, it
- does not matter which fraction is first or second. The answer in ç
- two cases will work out to be the same number.
-
- è First, you should change the operation to multiplication and invert
- the second fraction.
- êêêë16è12ê16è15
- #êêêë── ÷ ──è=è── ∙ ──
- êêêë 5è15ê 5è12
-
- Next, you should treat the problem as a multiplication problem.ïMulti-
- ply the two numerators and the two denominators.
-
- êêêè16è15êï16∙15
- #êêêè── ∙ ──è =è ─────
- êêêè 5è12êè5∙12
-
- Then, express each number in prime factored form.
-
- êêêë 16∙15êï2∙2∙2∙2∙3∙5
- #êêêë ─────è =è ───────────
- êêêê5∙12êè 5∙2∙2∙3
-
- Next, you should cancel out any like factors on the top and bottom.
-
- êêê2∙2∙2∙2∙3∙5êï2∙2
- #êêê───────────è =è ───
- êêêï5∙2∙2∙3êë1
-
- Finally, you should multiply any remaining factors.
-
- êêêêï2∙2
- #êêêêï───è=è4
- êêêêè1
-
- Thus, the quotient of 16/5 and 12/15 is 4.
-
-