using a graphing calculator to check simplification problems
DESCRIPTION
Using a graphing calculator to check simplification problems. You can always check your answer to a simplification problem using your calculator (or you can use another method that will be shown here). . This example is taken from the January 2010 Math B Regents (number 13). - PowerPoint PPT PresentationTRANSCRIPT
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USING A GRAPHING CALCULATOR TO CHECK
SIMPLIFICATION PROBLEMS
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You can always check your answer to a simplification problem using your calculator (or you can use another method that will be shown here). This example is taken from the January 2010 Math B Regents (number 13)
22 yxxy
This example is taken from the January 2010 Math B Regents (number 13)Which of the following is equivalent to
A B C D
yx 1
yx 1
yx 1
yx 1
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Without a calculatorChoose a value for x and y. Let’s say x = 2 and y = 1Now check the value you get when you substitute these values of x and y in the original expression and see what value you get
22 yxxy
22 1221
141
31
31
Now check each answer for x = 2 and y = 1 and see if you get -1/3
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A
B
C
D
yx 1 1
11
121
111
121
yx
1
yx 1
31
121
yx 1
31
31
121
This is the only one that has the same value as our original expression
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Using the graphing calculator to do this
You can store values for variables into your calculator. First we’ll store x = 2
Press the following sequence: 2, STO, XYour screen should show this Press enter:
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Now our calculator has x set equal to 2
We will do the same for y: we will store 1 into yThe sequence we will press is: 1, STO, APLHA, 1
Your screen should show this:
Press enter:
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Now check the value of the original expression using our values
22 yxxy
The sequence of keys we will press:Left parenthesis, ALPHA, 1, - (minus not negative), X, Right parenthesis, division symbol, left parenthesis, X, x^2 button, - (minus not negative), ALPHA, 1, x^2 button, ENTER
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After entering this sequence of buttons, this is what you should see on your screen:
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The next half:Here’s what you should have on your screen
Pressing enter you should get:
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If you want to convert your decimal to a fraction, press the following sequence:
MATH, 1 Here’s what you’ll see on your screen
Press ENTER
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Check the other expressions in a similar manner. The only answer that matches will be D.
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Be carefulYou must be careful about the values you choose for x and y
For example in our last example22 yxxy
We could not let x = y since that would cause division by 0 which is illegal.
You should only use this as a checking tool, NOT as your primary method of simplifying.