In general, the integer on the top of the fraction bar is called the numerator and the integer underneath the fraction bar is called the denominator.
Example: [latex]\frac{-5}{3}[/latex]
Negative 5 over 3 is a fraction in which -5 is numerator and 3 is the denominator.
These types of numbers are also referred to as rational numbers.
Properties:
1. If both the numerator ‘a’ and ‘b’ are multiplied by the same non-zero integer, the resulting fraction will be equivalent to a/b.
Example:
[latex]\frac{-5}{3}[/latex]
[latex]\frac{-5}{3}[/latex] = [latex]\frac{(-5)}{3}[/latex] * [latex]\frac{4}{4}[/latex] = [latex]\frac{-20}{12}[/latex]
Here, [latex]\frac{-20}{12}[/latex] is equivalent to [latex]\frac{-5}{3}[/latex]
[latex]\frac{-5}{3}[/latex] = [latex]\frac{(-5)}{3}[/latex] * [latex]\frac{(-1)}{(-1)}[/latex] = [latex]\frac{5}{-3}[/latex]
2. If both the numerator and denominator have a common factor, then the numerator and denominator can be reduced into an equivalent fraction.
Example 1:
[latex]\frac{40}{72}[/latex]
Numerator can be written as 8 * 5
Denominator can be written as 8 * 9
[latex]\frac{40}{72}[/latex] = [latex]\frac{(8 * 5)}{(8 * 9)}[/latex] = [latex]\frac{5}{9}[/latex]
Example 2:
By prime factorization
[latex]\frac{16}{20}[/latex] = [latex]\frac{(2 * 2 * 2 * 2)}{(2 * 2 * 5)}[/latex] = [latex]\frac{4}{5}[/latex]
Example 3:
By Greatest Common factor (GCF)
[latex]\frac{16}{20}[/latex] = [latex]\frac{(\frac{16}{4})}{(\frac{20}{4})}[/latex] = [latex]\frac{4}{5}[/latex]
Note:
Before solving any fractions first always reduce the fractions.
3. A fraction with a negative sign in either the numerator or denominator can be written with the negative sign in front of the fraction.
Example 1:
[latex]\frac{-5}{3}[/latex] = [latex]\frac{5}{-3}[/latex] = -[latex]\frac{5}{-3}[/latex]
Example 2:
[latex]\frac{-5}{-3}[/latex] = [latex]\frac{5}{3}[/latex] (Since - x - = +)
Addition and Subtraction
Same Denominator
To add two fractions with the same denominator, add the numerator and keep the same denominator.
Example:
[latex]\frac{1}{10}[/latex] + [latex]\frac{2}{10}[/latex] = [latex]\frac{(1 + 2)}{10}[/latex] = [latex]\frac{3}{10}[/latex]
To subtract two fractions with the same denominator, subtract the numerator and keep the same denominator.
Example:
[latex]\frac{5}{11}[/latex] – [latex]\frac{8}{11}[/latex] = [latex]\frac{(5 - 8)}{11}[/latex] = [latex]\frac{-3}{11}[/latex]
Same method is applied for adding or subtracting more than two terms
Example:
[latex]\frac{1}{5}[/latex] + [latex]\frac{2}{5}[/latex] + [latex]\frac{3}{5}[/latex] = [latex]\frac{(1 + 2 + 3)}{5}[/latex] = [latex]\frac{6}{5}[/latex]
Different denominator
To add two fractions with distinct denominators, first need to find a common denominator.
The common denominator is a common multiple of the two denominators, preferably the least common multiple (LCM).
Example:
[latex]\frac{2}{3}[/latex] + [latex]\frac{3}{4}[/latex]
LCM of 3 and 4 is 12.
[latex]\frac{((4 * 2) + (3 * 3))}{12}[/latex]
[latex]\frac{(8 + 9)}{12}[/latex]
[latex]\frac{17}{12}[/latex]
Similary, to subtract two fractions with distinct denominators, first need to find a common denominator.
Example:
[latex]\frac{1}{3}[/latex] – [latex]\frac{2}{5}[/latex]
LCM of 3 and 5 is 15.
[latex]\frac{((1 * 5) – (2 * 3))}{15}[/latex]
[latex]\frac{(5 - 6)}{15}[/latex]
= -[latex]\frac{1}{15}[/latex]
Same method is applied for adding or subtracting more than two terms
Example:
[latex]\frac{2}{3}[/latex] + [latex]\frac{1}{5}[/latex] – [latex]\frac{1}{2}[/latex]
LCM of 3, 5, 2 is 30
[latex]\frac{((2 * 10) + (1 * 6) - (15 *1))}{30}[/latex]
[latex]\frac{(20 + 6 – 15)}{30}[/latex]
[latex]\frac{11}{30}[/latex]
Multiplication
There is really nothing tricky about multiplying fractions.
When multiplying fractions all that is needed to do is multiply across each fraction's numerator and each fraction's denominator.
Example 1:
[latex]\frac{8}{3}[/latex] * [latex]\frac{7}{3}[/latex] = [latex]\frac{(8 * 7)}{(3 * 3)}[/latex] = [latex]\frac{56}{9}[/latex]
Note:
Always simplify fractions whenever possible.
Example 2:
[latex]\frac{4}{5}[/latex] * [latex]\frac{10}{12}[/latex] = [latex]\frac{(4 * 10)}{(5 * 12)}[/latex] = [latex]\frac{40}{60}[/latex] = [latex]\frac{4}{6}[/latex] = [latex]\frac{2}{3}[/latex]
Note: Do not try to simplify fractions while adding or subtracting the terms.
Need to find the common denominator, before adding or subtracting fractions.
When an integer is multiplied to a fraction
Example 1:
2 * [latex]\frac{4}{5}[/latex] = [latex]\frac{2}{1}[/latex] * [latex]\frac{4}{5}[/latex] = [latex]\frac{8}{5}[/latex]
Example 2:
[latex]\frac{3}{36}[/latex] * 3 = [latex]\frac{3}{36}[/latex] * [latex]\frac{3}{1}[/latex] = [latex]\frac{9}{36}[/latex] = [latex]\frac{1}{4}[/latex]
Division
Dividing fractions are just like the multiplying fractions.
To divide two fractions, invert the second fraction (find the reciprocal) before multiplying the fractions.
[latex]\frac{a}{b}[/latex] ÷ [latex]\frac{c}{d}[/latex] = [latex]\frac{a}{b}[/latex] * [latex]\frac{c}{d}[/latex] = [latex]\frac{ad}{bc}[/latex]
Example 1:
[latex]\frac{17}{8}[/latex] ÷ [latex]\frac{3}{4}[/latex] = [latex]\frac{17}{8}[/latex] * [latex]\frac{4}{3}[/latex] = [latex]\frac{(17 * 4)}{(8 * 3)}[/latex] = [latex]\frac{17}{6}[/latex]
Example 2:
[latex]\frac{4}{3}[/latex] ÷ 3 = [latex]\frac{4}{3}[/latex] ÷ 3 = [latex]\frac{4}{3}[/latex] * [latex]\frac{1}{3}[/latex] = [latex]\frac{4}{9}[/latex]
Complex fractions
A complex fraction is a fraction where the numerator, denominator or both contain a fraction.
ie. of the form [latex]\frac{\frac{a}{b}}{\frac{c}{d}}[/latex]
Example 1:
[latex]\frac{7}{\frac{1}{4}}[/latex] = [latex]\frac{7}{1}[/latex] ÷ [latex]\frac{1}{4}[/latex] = [latex]\frac{7}{1}[/latex] * [latex]\frac{4}{1}[/latex] = 28
Example 2:
[latex]\frac{\frac{3}{10}}{\frac{7}{13}}[/latex] = [latex]\frac{3}{10}[/latex] ÷ [latex]\frac{7}{13}[/latex] = [latex]\frac{3}{10}[/latex] * [latex]\frac{13}{7}[/latex] = [latex]\frac{39}{70}[/latex]
Mixed numbers
A mixed number (fraction) consists of an integer part and a fraction part.
Example:
[latex]4\frac{3}{8}[/latex]
[latex]4\frac{3}{8}[/latex] = 4 + [latex]\frac{3}{8}[/latex] = [latex]\frac{4}{1}[/latex] + [latex]\frac{3}{8}[/latex]
LCM of 1 and 8 is 8
[latex]\frac{(32 + 3)}{8}[/latex] = [latex]\frac{35}{8}[/latex]
Here, 35/8 is a improper fraction.
Improper fraction
It is defined as the fraction in which numerator is greater or equal to denominator.
Compare fractions
Two or more than two terms of fractions are given and need to compare them to find which is smaller and which is bigger among the given terms.
In order to compare, first find the common denominator.
Example:
Compare [latex]\frac{3}{7}[/latex] and [latex]\frac{7}{12}[/latex]
[latex]\frac{3}{7}[/latex] and [latex]\frac{7}{12}[/latex]
[latex]\frac{(12)(3)}{(12)(7)}[/latex] and [latex]\frac{(7)(7)}{(12)(7)}[/latex]
[latex]\frac{36}{84}[/latex] and [latex]\frac{49}{84}[/latex]
As the denominators are same, now compare the numerators
Like [latex]\frac{49}{84}[/latex] is bigger
[latex]\frac{36}{84}[/latex] is smaller
[latex]\frac{36}{84}[/latex] < [latex]\frac{49}{84}[/latex]
Fractions containing irrational numbers
The numbers of the form a/b may contain numbers in either ‘a’ or ‘b’ can be irrational numbers.
Example 1:
[latex]\frac{π}{2}[/latex] + [latex]\frac{π}{3}[/latex] = [latex]\frac{(3π +2π)}{6}[/latex] = [latex]\frac{5π}{6}[/latex]
Example 2:
[latex]\frac{π}{2}[/latex] * [latex]\frac{π}{3}[/latex] = [latex]\frac{π^2}{6}[/latex]
Example 3:
[latex]\frac{(\frac{π}{2})}{(\frac{π}{3})}[/latex] = [latex]\frac{π}{2}[/latex] * [latex]\frac{3}{π}[/latex] = [latex]\frac{3π}{2π}[/latex] = [latex]\frac{3}{2}[/latex]