# Solve the system of equations, using substitution or elimination by addition

August 30, 2017

Question
NAME:___________________________________________

I have completed this assignment myself, working independently and not consulting anyone except the instructor.

INSTRUCTIONS

· The quiz is worth 100 points. There are 7 problems, some with multiple parts. This quiz is open book and open notes. This means that you may refer to your textbook, notes, and online classroom materials, but you must work independently and may not consult anyone(and confirm this with your submission). You have to submit your answer document in your Assignments Folder in a readable format (.doc or .PDF format) no later than 11:59 pm on Sunday, Nov 8.

· Show work/explanation where indicated. Answers without any work may earn little or no credit.You may type or write your work in your copy of the quiz, or if you prefer, create a document containing your work. Scanned work (in jpg or pdf format is acceptable also. In your document, be sure to include your name and the assertion of independence of work.

1. (10 points)

Solve the system of equations, using substitution or elimination by addition (your choice). Show full work.

2x – 5y = 13

3x + 4y = -15

2. (10 points)

As chief financial officer at Apocalyptic Fitness Supply, you track costs and revenue for the daily manufacturing process for your company’s top-selling product, the SpineCrusher™ unstoppable elliptical trainer. Daily production costs \$12,000 plus \$15 for every unit produced. Daily revenue coming in equates to \$18 per unit sold minus flat daily rate of \$6000.

a. Determine the cost and revenue equations for this manufacturing process. Explain your answer.

Cost equation: C(x) = ___________________________________

Revenue equation: R(x) = ___________________________________

b. How many units must be sold each day for this manufacturing process to break even? Show algebraic work to find the answer.

Number of trainers sold daily to break even: _________________________

3. (15 points)

The Washington, DC average temperature in 1960 was 56.3 degrees. In 2012, the Washington, DC average temperature was 61.5 degrees. Let y be the Washington, DC average temperature in the year x, where x = 0 represents the year 1960.

(a) Find a linear equation which could be used to predict the Washington, DC average temperature y in a given year x, where x = 0 represents the year 1960. Explain/show work.

(b) Use the equation from part (a) to estimate the Washington, DC average temperature for the year 2020. Show some work.

(c) Interpret the slope of the equation in part (a) by filling in the blanks: The rate of change of theaverage Washington DC temperature is per

(include units of measurement).

4. (10+5+5+15 = 35 points)

Given the points (-3, -2) and (-1, 4):

a) Write an equation in point-slope form of the line L1 through the points. Show work.

b) Convert the equation of L1 to slope-intercept form. Show work.

c) State the intercepts of the line L1. Both intercepts should be stated as ordered pairs.

x-intercept:

y-intercept:

d) Determine the slope-intercept equation of a line L2 which is perpendicular to L1 and passes through the point (-1, -2). Show work

5. (5 points)

a) Write an equation of a vertical line through the point (-5, -3).

b) Write an equation of a horizontal line through the point (6, -7).

6. (15 points)

Solve the inequality: −5 £ 2 .

Write your answer in interval notation and graph the solution set on a number line. Show work.

If you are typing the exam, you can easily create a number line and graph inequalities using your keyboard. “How-to” link is in Content > Table of Contents > Course Resources > Webliography in our LEO classroom

7. (10 points)

Roy is selling his car through a broker. Roy wants to get \$4500 for himself, but the broker gets 10% of the selling price as commission. What should the selling price be? Show algebraic work to find the answer.

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