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Cross Product Property

Rule

Cross Product Property

The cross product property, also known as cross-multiplication, is a faster method to simplify an equation which has fractions on both sides of the equal sign. An example is x5=27.\frac{x}{5}=\frac{2}{7}.

Korsmultiplicera rules.svg
The procedure is that both sides are multiplied by 55 and 7,7, the denominators of both sides. The result is that the denominators and multiplier undo each other.
x5=27\dfrac{x}{{\color{#0000FF}{5}}}=\dfrac{2}{{\color{#FF0000}{7}}}
x75=2\dfrac{x\cdot {\color{#FF0000}{7}}}{{\color{#0000FF}{5}}}=2
x7=52x\cdot {\color{#FF0000}{7}}= {\color{#0000FF}{5}} \cdot 2
With cross multiplication, these steps are done at the same time.