Aim; How do we solve proportions by using cross product.?

1.)Explain; how the term cross product can help you remember how to solve a product.?

2/5= x/35

Fists you cross multiply.

x5=70

Second you find the variable.

5÷70= 14

x=14

2.)Describe; the error in these steps: 2/3= x/12; 2x=36; x=18

First; They cross multiply wrong: 2(12)=24

Second; He had to put 3x=24: you had to divide 3÷24 and the answer would be x=8

3.)Show; how to use cross product to decide whether the ratios 6:45 and 2:15 are proportional.

You have to cross multiply 6(15)=90 and 45(2)=90

It has the same sum, so it is proportional.

## Friday, April 3, 2009

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