- Thread starter ebrushman
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As far as I know, there is NO definite check for that!ebrushman said:After I simplify this, is there a check to know I'm right?

3y-15 / 3y+15

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ebrushman said:After I simplify [3y-15 / 3y+15], is there a check to know I'm right?

You can sort of cheat with a graphing calculator: Graph the original expression as "Y1", and, on the same screen, graph your final expression as "Y2". If the two lines are the same, then you probably did the simplification correctly. :wink:Subhotosh Khan said:As far as I know, there is NO definite check for that!

Eliz.

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Stapel's method described above - using a graphing calculator - will tell you DEFINITELY whether you have reduced CORRECTLY or not.

However, it CANNOT tell you whether further simplification is possible or not.

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(3Y - 15) / (3Y + 15)

Put Y = 0

(3*0 - 15) / (3*0 + 15)

-15 / 15

= -1

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now put Y = 0 for (Y - 5)/(Y + 5)

(0 - 5)/ (0 + 5)

-5 / 5

= -1 ... matches -1 above

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ebrushman said:After I simplify [3y-15 / 3y+15], is there a check to know I'm right?

Actually, this technique gets students into a lot of trouble later on, specifically in checking trig identities.scoresofsteel said:Putting Y = 0 will be a fast way of knowing that.

By checking only one point, you only verify that the two expressions evaluate the same

Eliz.

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