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If a recipe calls for half a cup of flour and half a cup of sugar, you could say you need half a cup of the flour-sugar mix combined. In algebra, pulling out that shared fraction is called factoring.
A rational coefficient is any fraction or decimal multiplying a variable, such as 21β in 21βx or 0.75 in 0.75y. Factoring simply runs the distributive property in reverse to pull that number outside parentheses.
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What happens when you factor a fraction out of a whole number, like pulling 31β out of 2?
Factoring Out Unit Fractions
To factor out a fraction like 31β, divide every term inside the expression by 31β. Since dividing by a fraction means multiplying by its reciprocal (flip), dividing by 31β is the same as multiplying by 3.
Let's factor 31β out of the linear expression 31βxβ2. Dividing 31βx by 31β leaves x, and dividing β2 by 31β gives β2Γ3=β6, resulting in 31β(xβ6).
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How do we choose which fraction to pull out when the terms have different denominators, like 21βx+41β?
Finding a Common Fractional Factor
When terms have different fractions, factor out the fraction with the least common denominator so that the terms inside parentheses become whole integers. For 21βx+41β, the common denominator is 4, so we factor out 41β.
Dividing 21βx by 41β gives 21βΓ4=2x, and dividing 41β by 41β gives 1. The expression becomes 41β(2x+1).
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