Solving Systems by Substitution
7.2 Solving Linear Systems by Substitution
Ex. 1 Solve the linear system
-x + y = 1 2x + y = -2
1) solve for y in equation 1.
2) substitute ______ for y in equation 2.
3) To find y substitute ____ in for x.
4) Check with original equation.
-x + y = 1
2x + y = -2
Solving Systems by Substitution
Solve each linear system using substitution.
1. 2x + 2y = 3
x - 4y = -1
2. x - y = 2
2x + y = 1
3. 2x + 3y = 31
4. x - y = -5
5.
6. m + 2n = 1
y=x+7
2a = 8
a+b=2
x + 4 = 16
5m + 3n = -23
Solving Systems by Substitution
Solve each system using substitution.
When solving systems with quadratics, always
a) solve for y in both equations.
b) set the equations equal (plug in for y).
c) solve for x.
d) plug x into linear equation and evaluate for y.
1. y = x2 + 6x + 9
y = -x - 1
2. y = x2 +2x + 3
y=x+5
3. y = -2x -16x - 33
2x - y = -3
2
4. y = 2x - 4x
2x + y = 3