Proportions

1
Proportions

• Solving proportions

2
Reciprocal Property of Proportions

• If two ratios are equal, then their reciprocals
  are also equal.

Example
3
Solve the proportion using the reciprocal
property.
Use the reciprocal property
12
1
60
60
Multiply by 60 to clear the denominators.
1
1
So x 24
4
Cross Product Property of Proportions
Example
5
Solve the proportion using the cross product
property.
Use the cross product property
1
Divide by 5 to isolate y
5 5
1
6
Solve the proportion using the cross product
property.
Use the cross product property
Now multiply
Subtract 12
Now factor the quadratic
0 (x 4)(x 3)
x40 x 3 0
x -4 or x 3
7
Solve the proportion using the cross product
property.
Use the cross product property
Use the distributive property
Multiply
Combine like terms
But y ? - 3 because a denominator of 0 is not
allowed. So
-y2 18 -y2 18
y2 9