Day 62 – November 18

Algebra: Chapter 8 Benchmark!

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Algebra 1a: Chapter 3, Lesson 9, page 148.

Proportions

A ratio of 2 quantities is a comparison, often expressed as a fraction. An equation that states that 2 ratios are equal is called a proportion. I prefer to just criss-cross, or cross multiply proportional problems, but the book’s way is OK too.

For example,

`x/63=2/9`, I solve by criss-crossing. That becomes

`x*9=2*63` or `9x=63*2` or `9x=126`

and dividing both sides by 9 to clear the x, gives us `x=14`.

Here is a link from purplemath.com that has some more examples.

Two of tonight’s homework problems solved by MrE are here! Just click it!

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