Section 3-1
Proportions
A proportion is an equation in the form
These can be solved using the means-extremes property, which says that in such an equation,
ad = bc.
This is also known as cross-multiplying or taking cross products.
Example:
Solve for x.
Use the means-extremes property to get a simpler equation.
3(9) = 7(x + 1)
Now simplify and solve.
27 = 7x + 7
7x = 20