Download Alg 2-3.1

Algebra II
Section 3.1: Solving Systems Using Tables and Graphs
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Solution:
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Notes #:
Objective:
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To solve a system of equations by graphing:
1) Put each equation in slope intercept form: y = mx + b
2) Graph each equation
3) You may need to zoom out to see the intersection—follow this
order with your zooming:
Zoom 6 (Standard)
Zoom 0 (Fit)
Zoom 3 Enter-over and over again until you can see
the intersection in the window
4) 2nd trace 5 (intersect) enter enter enter
Example 1) Solve the following
system by graphing:
3y =-7x + 6
6y + 14x = -24
Example 2) Solve the following
system by graphing:
4y  x  8
3
x y 6
4
Example 3) Solve the following
system by graphing:
1
2
x y 1
2
3
3x  4 y  6
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Algebra II
Section 3.1: Solving Systems Using Tables and Graphs
Notes #:
Objective:
We will often use a system of equations to solve word problems!
These key phrases mean to find the intersection point:
“break even”, “surpass”, “make a profit”
Example 4) Travis and his band are planning to record their first CD. The initial start-up cost is $1500, and
each CD will cost $4 to produce. They plan to sell their CDs for $10 each. How many CDs must the band sell
before they make a profit?
x represents: ____________________
y represents: ______________________
Equation 1: Cost to produce CDs __________________
Equation 2: Income from selling CDs ________________
(x,y) answer: ___________
Word answer: __________________________
Example 5) Laura’s Copies has two options for buying photocopies. With Option 1, you can buy a
card for $40 each year and then pay $0.03 per copy. With Option 2, you can just pay $0.05 per
copy. For how many copies would the cost of Options 1 and 2 be the same? What is the cost?
x represents: ____________________
y represents: ______________________
Equation 1: __________________________
Equation 2: __________________________
(x,y) answer: ___________
Word answer: __________________________
Example 6) The Waxmans just opened a carpet store. Their startup costs were $5000, and their cost of carpet
is $8 per square yard. How many square yards of carpet do they need to sell in order to break even if they sell
the carpet for $18 per square yard?
x represents: ____________________
y represents: ______________________
Equation 1: __________________________
Equation 2: __________________________
(x,y) answer: ___________
Word answer: __________________________