3x - 5y = 15 and y = x + 1. Write the solution to this system of linear equations by typing the intersection point from your TI-83 Plus.

Question

Use your TI-83 Plus to find the solution for this system of equations:  IMPORTANT: Both your x and y values should be integers. Remember that the format for a point is (x,y). For BrainHoney's sake, no spaces please.

Answer 1

Dear Caleb,

   The second equation is written in "Y=X+1."  You need to solve for the first equation for "Y" also, so that you can enter these equations in the graphing mode of the calculator, which is your first function, upper left; it says, "Y=."

Let's look at 3X-5Y=15.

 

1.  You can add 5Y to both sides of the equation:   3X-5Y+5Y=5Y+15.

 

2.  Subtract 15 from both sides to isolate "5Y."       3X-15=5Y.

 

3.  Now, divide "5Y" by the number next to it.            (3/5)X-15/5  =(5/5) Y.

 

4.  Then simplify, and you get (3/5)X - 3 =Y.  Enter this equation into the graphing calculator.

 

5. After you have both equations entered, press "GRAPH."

 

6.  If you want to see the intersection of the two lines a little better, go to function 2, "WINDOW."

 

7.  Change the X-min to X-min=-20  and Y-min=-15; then press "GRAPH" again.

 

8. To find the "intersect" button, go to 4th function called "TRACE."  "Intersect" is number 5 on the list.

 

9.  When you press it, it is asking for a guess, but all you need to do is press the "ENTER" button three times.  You will see the word "Intersection."  The two lines intersect at those X and Y values.  Just write it into a coordinate point.

Note:  This intersection point is the same for both lines.  It is the solution to this system of equations.  Check this out in the table function, which is right below the "GRAPH" function.  Just press the "2nd" button on the left, right below the "Y=" button.

Go to the "X=-10" and Y1 and Y2= same values.

10.  I am going to let you find the complete values for the coordinate point.

 

If I have helped you, please give me a thumbs up.

                                                                                  Susan C.