Sewanhaka High School
Math 8
Per:________________
Name:________________________________
Mrs. Lidowsky, Principal
Mr. Long, Teacher
Date:_____________________
H.W. #42: Ditto
DO-NOW #42:
1) Graph the system of equations: 2x + y = 5
and y = ½x, and check the solution.
2) I am thinking of two numbers. One number is three times the other. Their sum is 12. What are the numbers?
Topic: Equations and Expressions
Main Idea: Using Substitution to solve a system of equations
Aim:
RECALL
NOTES
In Do – Now question #2, you solved for the missing
numbers in terms of one variable, mainly x.
Would it be possible to solve for Do – Now question
#2 in terms of two variables algebraically?
If we look at Do – Now question #2, what term did
we use to represent the second number?
Solve the system of equations by using substitution:
y = 2x + 5
x + y = 11
Solve the system of equations by using substitution:
A) x = 2y + 4
B) x + y = 10
Solve the system of equations by using substitution:
A) x = 2y + 4
B) x + y = 10
Math 8 – LP #42 – Page 2
Drill: Do questions 1 and 2. If time, we will go back to 3 and 4.
Use substitution to solve the following systems of equations algebraically and make sure to check:
1) y = 2x + 5
x + y = 17
Summary:
2) a = 2b - 4
a – b = 10
3) x + y = 6
2x + y = 10
4) w = r + 4
2w + 3r = 13