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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).
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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) This example is taken from the January 2010 Math B Regents (number 13) Which of the following is equivalent to A B C D
Without a calculator Choose a value for x and y. Let’s say x = 2 and y = 1 Now check the value you get when you substitute these values of x and y in the original expression and see what value you get Now check each answer for x = 2 and y = 1 and see if you get -1/3
A B This is the only one that has the same value as our original expression C D
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, X Your screen should show this Press enter:
Now our calculator has x set equal to 2 We will do the same for y: we will store 1 into y The sequence we will press is: 1, STO, APLHA, 1 Your screen should show this: Press enter:
Now check the value of the original expression using our values 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
After entering this sequence of buttons, this is what you should see on your screen:
The next half: Here’s what you should have on your screen Pressing enter you should get:
If you want to convert your decimal to a fraction, press the following sequence: Here’s what you’ll see on your screen MATH, 1 Press ENTER
Check the other expressions in a similar manner. The only answer that matches will be D.
Be careful You must be careful about the values you choose for x and y For example in our last example 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.