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Solution 1.2:2a

From Förberedande kurs i matematik 1

Revision as of 07:42, 19 September 2008 by Tek (Talk | contribs)
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A common way to calculate the expression in the exercise is to multiply top and bottom of each fraction by the other fraction's denominator, so as to obtain a common denominator,

61+110=611010+11066=6010+660.

However, this gives a common denominator, 60, which is larger than it really needs to be.

If we instead divide up the fractions' denominators into their smallest possible integral factors,

123+125,

we see that both denominators contain the factor 2 and it is then unnecessary to include that factor when we multiply the top and bottom of each fraction.

61+110=6155+11033=530+330.

This gives the lowest common denominator (LCD), 30.