Page 371 - Algebra 1

Solving with a Graphing Calculator
Use a graphing calculator to solve the system and then check your solution. 2x + y = -2
y = -3x - 5 SOLUTION Write 2x + y = -2 in slope intercept form.
2x + y = -2 -_ 2 _ x = -_ _ 2 x _
y = -2x - 2 Graph both equations and then use the
intersection command.
The intersection point is (-3, 4).
Check that the ordered pair (-3, 4) makes both original equations true.
Example
4
Graphing Calculator Tip
For help with graphing systems, see the Graphing Calculator Lab 5 on page 352.
of the system.
2x + y = -2 2(-3) + 4 -2 -6 + 4 -2
y = -3x - 5
4 -3(-3) - 5 4 9 - 5
4 = 4 ✓
-2 = -2 ✓
The ordered pair (-3, 4) is a solution of each equation. (-3, 4) is a solution
Example
5
Application: Rate Plans
Beau and Celine decide to rent bikes. There are two shops from which to choose. Rent-a-Bike charges $10 per hour per bike. Bike-o-Rama charges only $4 per hour per bike, but with a deposit of $15 per bike. At what number of hours will both shops charge the same amount? What is that amount?
SOLUTION First write a system of equations.
Rent-a-Bike: amount charged = rate · hours y = 10x
Bike-o-Rama: amount charged = rate · hours + deposit y = 4x + 15
Graph the equations.
Find the intersection of the two lines using a graphing calculator.
intersection point: (2.5, 25)
At 2.5 hours, both shops will charge $25.
Graphing Calculator Tip
Adjust the graphing window to view the intersection.
356 Saxon Algebra 1