7x - 3y = 63 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

I don't have a TI-83 with me, but we can use Wolfram Alpha:

 

http://www.wolframalpha.com/input/?i=plot+7x+-+3y+%3D+63+and+y+%3D+x+-+1

 

By inspection, the intersection point is at (15,14). Plug this back into the original equations to double check:

 

7(15) - 3(14) = 105 - 42 = 63 OK

 

14 = 15 - 1 OK

Answer 2

Rewrite the first equation so that y is isolated on one side of equation.

 

-3y = -7x + 63    ---->  y = (7 / 3)x - 21

 

On your calculator, press the Y= key.  Type in the equations exactly as you see them.  Let \Y₁ be the first equation.  Let \Y₂ be the second equation.  Then press GRAPH key.  You will see your lines being graphed.  Next, press 2ND, TRACE, and scroll down to select intersect.  Hit ENTER three times, and the calculator will give you your point of intersection.

 

You may need to change your windows.  Change these parameters in WINDOW:

 

Xmax = 20

Ymax = 20