Solution 1.2:4b
From Förberedande kurs i matematik 1
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- | {{ | + | Multiply top and bottom of the double fraction by the reciprocal of the denominator, |
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- | {{ | + | {{Displayed math||<math>\frac{\displaystyle\,\frac{2}{7}\,}{\displaystyle\,\frac{3}{8}\,} = \frac{\displaystyle\,\frac{2}{7}\cdot \frac{8}{3}\,}{\displaystyle\,\frac{\rlap{/}3}{\rlap{/}8}\cdot \frac{\rlap{/}8}{\rlap{/}3}\,}=\frac{2}{7}\cdot \frac{8}{3}\,</math>.}} |
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+ | The numerator and denominator on the right-hand side do not have a common factor, so the answer is | ||
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+ | {{Displayed math||<math>\frac{2}{7}\cdot \frac{8}{3}=\frac{2\cdot 8}{7\cdot 3}=\frac{16}{21}\,</math>.}} | ||
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+ | Note: It is also possible to learn a quick formula for double fractions which says that when the expression is rewritten with just one fraction sign, the denominators in the partial fractions change place, | ||
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+ | {{Displayed math||<math>\frac{\displaystyle\,\frac{2}{7}\,}{\displaystyle\,\frac{3}{8}\,}=\frac{2\cdot 8}{3\cdot 7}\,</math>.}} |
Current revision
Multiply top and bottom of the double fraction by the reciprocal of the denominator,
\displaystyle \frac{\displaystyle\,\frac{2}{7}\,}{\displaystyle\,\frac{3}{8}\,} = \frac{\displaystyle\,\frac{2}{7}\cdot \frac{8}{3}\,}{\displaystyle\,\frac{\rlap{/}3}{\rlap{/}8}\cdot \frac{\rlap{/}8}{\rlap{/}3}\,}=\frac{2}{7}\cdot \frac{8}{3}\,. |
The numerator and denominator on the right-hand side do not have a common factor, so the answer is
\displaystyle \frac{2}{7}\cdot \frac{8}{3}=\frac{2\cdot 8}{7\cdot 3}=\frac{16}{21}\,. |
Note: It is also possible to learn a quick formula for double fractions which says that when the expression is rewritten with just one fraction sign, the denominators in the partial fractions change place,
\displaystyle \frac{\displaystyle\,\frac{2}{7}\,}{\displaystyle\,\frac{3}{8}\,}=\frac{2\cdot 8}{3\cdot 7}\,. |