Ian at 12:38, 11 September 2008

Ian — Thu, 11 Sep 2008 12:38:21 GMT

←Older revision	Revision as of 12:38, 11 September 2008
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	+	We divide up the two numerators into the smallest possible integer factors,

	+
	+	<math>\begin{align}
	+	& 12=2\centerdot 6=2\centerdot 2\centerdot 3 \\
	+	& 14=2\centerdot 7 \\
	+	\end{align}</math>
	+
	+	The expression can thus be written as
	+
	+
	+	<math>\frac{1}{2\centerdot 2\centerdot 3}-\frac{1}{2\centerdot 7}</math>
	+
	+	Here, we see that the denominators have a factor
	+	<math>2</math>
	+	in common. We multiply the top and bottom of the first fraction by
	+	<math>7</math>
	+	and the second by
	+	<math>2\centerdot 3</math>
	+	i.e. we leave out the common factor
	+	<math>2</math>
	+	, so that the fractions have the lowest common denominator
	+	<math>2\centerdot 2\centerdot 3\centerdot 7</math>
	+	,
	+
	+
	+	<math>\frac{1}{12}-\frac{1}{14}=\frac{1}{2\centerdot 2\centerdot 3}-\frac{1}{2\centerdot 7}=\frac{1}{2\centerdot 2\centerdot 3}\centerdot \frac{7}{7}-\frac{1}{2\centerdot 7}\centerdot \frac{2\centerdot 3}{2\centerdot 3}</math>
	+
	+	The lowest common denominator is
	+	<math>84</math>
	+	.

Lina at 09:59, 26 March 2008

Lina — Wed, 26 Mar 2008 09:59:27 GMT

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