1. 5.3 Elimination
Eliminate means to get rid of…so lets get rid of a variable by adding the two equations together.
-3x + 4y = 12
3x - 6y = 18
-2y = 30
y = -15
Now substitute the y value of -15 back into one of the original equations to solve for x.
-3x + 4(-15) = 12
-3x – 60 = 12
-3x = 72
x = - 24
Answer: (-24, -15) +

2. Try this one x + y = 7 x – y = 9 2x = 16 x = 8 8 + y = 7 y = -1
Answer: (8, -1) +

3. Example
4x – 3y = 12
2x + 3y = 6
6x = 18
x = 3
4(3) – 3y = 12
12 – 3y = 12
-3y = 0
y = 0
The two numbers are 3 & 0
Four times one number minus three times another number is 12. Two times the first number added to three times the second number is 6. Find the numbers. +

4. Same applies with subtraction Remember to change all the signs when you subtract.
4x + 2y = 28
4x - 3y = 18
5y = 10
y = 2
4x + 2(2) = 28
4x + 4 = 28
4x = 24
x = 6
(6, 2)

5. Try this one 8x + y = 16 -6x + y = -26 14x = 42 x = 3 8(3) + y = 16
(3, -8)
p. 268 #1-4
1. (-1, 3)
2. (-2, -1)
3. (0, -5)
4. (-2.5, -2)
Practice Worksheet
#3, 5, 7, 11
Homework #36
p all, odd, 33-34