1. ALGEBRA II HONORS/GIFTED @
ALGEBRA II HONORS/GIFTED - SECTIONS 3-1 and 3-2 (Solving Systems of Equations)
ALGEBRA II HONORS/GIFTED @
SECTIONS 3-1 and 3-2 : SOLVE LINEAR SYSTEMS OF EQUATIONS

2. 1) Solve by graphing.
2x + y = 8
3x – 2y = -2
Solve for y.
y = -2x + 8
Find the intercepts.
x-int : -2/3
y-int : 1
The point of intersection
is (2, 4)
Note that 2(2) + 4 = 8 and
3(2) – 2(4) = -2

3. 2) Solve by substitution.
3x – 2(-2x + 8) = -2
3x + 4x – = -2
7x – = -2
7x = 14
x = 2
2x + y = 8
3x – 2y = -2
Look for the equation where solving for x or for y is easiest.
Substitute 2 for x for find y.
y = -2(2) + 8
= 4
Solve for y in the top equation.
y = -2x + 8
Next, substitute into the other equation and solve.
3x – 2y = -2
Therefore, the answer is (2, 4)

4. 3) Solve using elimination
2 • (2x + y) = 8 • 2
3x – 2y = -2
4x + 2y = 16
3x – 2y = -2
2x + y = 8
3x – 2y = -2
7x = 14
x = 2
The goal is to make opposites for one of the variables and add the equations together.
Substitute 2 for x into either original equation to find y.
2(2) + y = 8
4 + y = 8
y = 4
Multiply the top equation by 2 to make 2y on top to go along with the -2y on bottom.
Therefore, the answer is (2, 4)

5. Elimination (linear combination)
METHODS FOR SOLVING SYSTEMS OF EQUATIONS :
Graphing
Substitution
Elimination (linear combination)
????

6. Solve using the method of your choice.
4) 3x – 7y = 31
2x + 5y = 11
5) 4x + 3y = 10
5x y = 22
ANSWER : (8, -1)
ANSWER : (4, -2)

7. 6) 2x – 3y = 12
y = -2x + 4
Just in case you want it!!
ANSWER : (3, -2)

8. 7) y = x + 1 y = x – 2 8) 2x – 4y = -16 -x + 2y = 8
If the variables cancel
false statement
no solutions
parallel lines
true statement
infinite solutions
same lines

9. 9) 4x – 3y = 11
5x – 6y = 9
10)
(2, -3)
11) Silver Alloy Problem. Old silver coins contain 90% silver. Silver solder contains 63% silver. If you wanted to make 200 kg. of an alloy containing 82% silver, how many kg. of old coins and how many kg. of silver solder could you melt together to do this?
kg. coins and kg. silver solder

10. NAMES FOR SYSTEMS OF EQUATIONS
ALGEBRA II HONORS/GIFTED - SECTIONS 3-1 and 3-2 (Solving Systems of Equations)
NAMES FOR SYSTEMS OF EQUATIONS
Inconsistent equations
Parallel lines
Dependent equations
Coincidental lines
Independent equations
Intersecting lines

11. Without graphing, classify each system as independent, dependent, or inconsistent.
11) 4x – 5y = 0
3x – 5y = -5
12) -20x + 12y = -24
5x y = 6
ANSWER :
independent
ANSWER :
dependent
13) 3x - y = 2
6x – 2y = 5
ANSWER :
inconsistent