Using the TI-84 plus to solve two linear equations simultaneously

Uploaded by hackingmathsOFFICIAL on 23.04.2012

Hi and welcome to another edition of hackingmaths.
Today we are going to use the TI-84plus to solve two equations simultaneously.
To do this the equations must be in the form Ax + By = C.
I will not cover rearranging equations of straight lines in this lesson.
So let's begin.
We need to use the MATRIX function on the calculator.
Press 2ND and then x to the minus one.
This takes us into the MATRIX menu.
Now scroll to the RIGHT twice.
This take us to the edit menu.
You'll notice that [A] is highlighted. This means that we will be editing MATRIX A.
We could choose anyone of the other MATRICES to edit but I always use MATRIX A.
Press ENTER.
As there are two equations. We need to tell the calculator that there are two ROWS Type 2 and press ENTER for the number of ROWS.
We then type 3 and press ENTER to tell the calculator that there are three COLUMNS.
Now we enter the coefficients of the letters into the MATRIX.
The coefficients are just the numbers infront of the letters.
So we type 3 as that is infront of the x. Press ENTER.
We type minus 2 as that is infront of the y. Then press ENTER.
Then we type 10 and press ENTER.
We then do the same for the next equation.
Type 4. Press ENTER.
Type 3. Press ENTER.
Type 19. Press ENTER.
Now we have entered the equations into the calculator.
So we need to leave the MATRIX.
So we press 2ND and then MODE.
To solve these equations simultaneously we do the following:
press 2ND x to the minus 1. (This takes us back into the MATRIX menu).
Scroll to the right once.
Scroll up until you reach rref(
Once rref( is highlighted like mine ress ENTER. This selects the rref( function.
Now we need to tell the calculator which matrix to use.
So press 2ND then x to the minus 1.
If you put your equations into MATRIX A like I did, just press enter.
Otherwise scroll down, highlight the MATRIX that you used and then press ENTER.
You can close the brackets but it isn't necessary now and press ENTER again.
We have now solved these two equations simultaneously.
But what does this result mean?
Well as we put all our X-values into the first column, all the Y-values into the second column and our numbers into the third column
this means that one x equals 4 and one y equals 1.
Thanks for watching this episode and we'll see you next time on hackingmaths.