Elimination Week 17 blog post

Add or subtract In elimination, we have to add or subtract two linear equations to isolate one of the variables. So, the first thing to look for is wither you should add or subtract two equations. To find out which one, you simply look at the equations and see which one will make a zero pair. Ex; X+2y=4 -X+6y=12 Would be added because then the Xs would be canceled out and the only remaining variable would be Y.

Find the isolated Variable Now that we have only 1 variable left (can be X or Y) we must find its value. To do this, we use algebra on the single equation left after the first step. Ex; X+2y=4 -X+6y=12 Added is now 8y=16 y=2

Find the missing variable Now that we have 1 variable, we can find the other. To do this, we must substitute the value of the variable into one of the original equations. It can be either one. Ex; X+2y=4 (Y=2) X+2X2=4 X=4-4 X=0

Check If you want to check to make sure your answers are right, you can check by putting the values of the variables back into the original equations. If both sides are equal, then the values are right. Ex; X=0 Y=2 X+2y=4 -X+6y=12 1X0 + 2X2 = 4 -1X0 +6X2=12 4=4 12=12