systems of equations.notebook
October 12, 2016
2x + 4y = 8
{ -2x + 3y = 13
Notice how this system would be problematic to graph,
and not-so-easy to apply substitution.
2x + 4y = 8
{ -2x + 3y = 13
1.
Find a variable which has an additive inverse. If no
additive inverse exists, multiply to create an additive inverse.
2x + 4y = 8
-2x + 3y = 13
2.
Add the equations like you would normally add two
numbers. One variable should disappear.
2x + 4y = 8
-2x + 3y = 13
7y = 21
0
3.
Solve for the variable.
7y = 21
y=3
4.
Plug back into the easiest equation and solve for the
missing variable.
2x + 4y = 8
2x + 4(3) = 8
2x + 12 = 8
2x = -4
x = -2
5.
Check both equations for correctness.
{ 6x + 5y = 26
3x - 5y = 10
systems of equations.notebook
October 12, 2016
Elimination
x - y = 11
5x + y = 9
2x + y = 19
10x - 7y = -18
-2x - 9y = -25
-3x + 7y = -16
-4x - 9y = -23
-9x + 5y = 16
8x + 3y = 21
5x - 4y = 19