SUBSTITUTION EXAMPLE
3X+4Y=-4
X+2Y=2
1. SOLVE EQUATION 2 FOR X
X=-2Y+2
2. SUBSTITUTE THE EXPRESSION FOR X INTO EQUATION 1 AND SOLVE FOR Y
3(-2Y+2)=4Y
SOLVE ANDYOU GET
Y=5
3. SUBSTITUTE THE VALUE OF Y INTO REVISED EQUATION 2 AND SOLVE FOR X.
X=-2(5)+2
SOLVE
X=-8
THE SOLUTION IS
(-8,5)