Download 7.1A Solving systems graphically and substitution

Precalculus
7.1A Systems of Equations-Solve by Graphing and Substitution
Method of Substitution:
1. Solve one of the equations for one variable in terms of the other.
2. Substitute the expression found in step 1 into the other equation to obtain an equation of
one variable.
3. Solve the equation obtained in step 2.
4. Back-substitute the solution in step 3 into the expression obtained in step 1 to find the
value of the other variable.
5. Check the solution to see that it satisfies each of the original equations.
Example #1:
Solve the following system of equations using substitution.
a)
x y 4
x y 2
b)
1
1
x y 8
5
2
x + y = 20
Example #2:
Solve the following system of equations. Verify your answer graphically.
x2  x  y  1
 x  y  1
Example #3:
Solve the following system of equations. Verify your answer graphically.
x y 4
x2  y  3
Example #4: Solve the system.
Example #5: Solve.
y = -x2
y = x2 – 4x
−3𝑥 + y = 5
-5x + 3y = 6
Assignment 7-1A Pg. 481 #6-36 even
5