Adding and/or Subtracting Fractions with Different Denominators

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Jason
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Joined: Sun Dec 21, 2025 8:56 pm

In the case of different denominators, you multiply each fraction by a fraction of a number over the same number that will cause the least common multiple (LCM) of the denominators to be the new denominator of each fraction.

Next, you simply add and/or subtract or subtract and/or add the new numerators while the answer's denominator is still the LCM.
:?: What's the answer?
\(\dfrac{4}{7} + \dfrac{1}{2}\)
:arrow:
\(7 \longrightarrow 7^{1}\)

\(14 \longrightarrow 7 * 2 \longrightarrow 7^{1} * 2^{1} \)
The highest pairs of prime power/powers are:
\(7^{1}\)
The highest solo prime power/powers are:
\(2^{1}\)
:arrow:
\(LCM = 2^{1} * 7^{1} = 14^{1} = 14\)
:arrow:
\(A: 7(x) = 14 \longrightarrow x = 2\)

\(B: 2(x) = 14 \longrightarrow x = 7\)


\(\dfrac{4}{7} + \dfrac{1}{2} \longrightarrow \dfrac{4}{7} * \dfrac{2}{2} + \dfrac{1}{2} * \dfrac{7}{7} = \)
\(\dfrac{8}{14} + \dfrac{7}{14} = \dfrac{15}{14}\)
Can this be reduced?

\(15 \longrightarrow 3 * 5 \longrightarrow 3^{1} * 5^{1}\)

\(14 \longrightarrow 2 * 7 \longrightarrow 2^{1} * 7^{1}\)

The lowest prime/powers common to both numbers are:
none

\(GCF = 1\)
:arrow:
The answer cannot be reduced.
 

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