Student Worksheet (Page 2 of 2) in pdf

Student Worksheet Page 2

SHOPPING

(Systems of Linear Equations – Standard Form)

Answer Key

1. Write a system of equations that could be used to determine the cost of one pair of jeans (x)

and the cost of one tee shirt (y).

2x + 6y = 60

4x + 3y = 75

2. Solve each equation for y. Enter the equations into your calculator.

Y = (-1/3)x +10

Y = (-4/3)x +25

3. Set up an appropriate graphing window, and then graph the equations.

4. Use your calculator to find the point of intersection of the two lines.

(15, 5)

5. What is the meaning of this point of intersection in the context of this problem? Use

mathematics to justify your answer.

The x value of the point of intersection is the cost of a pair of jeans and the y value is the

cost of a tee shirt. This is true because the point of intersection of two lines is the point

that makes both equations true.

6. How much does each pair of jeans cost? Use mathematics to explain how you determined

your answer. Use words, symbols, or both in your explanation.

A pair of jeans cost $15.

Example explanation: I found this by determining the x value of the point of intersection.

7. How much does each tee shirt cost? Use mathematics to explain how you determined your

answer. Use words, symbols, or both in your explanation.

A tee shirt cost $5.

Example explanation: (algebraic)

2x + 6y = 60

-4x –12y = -120

4x + 3y = 75

___________

-9y = -45

y = 5

tee shirts cost $5

Lesson Plan: Systems of Linear Equations – Standard Form

Page 2

Student Worksheet Page 2