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Study Guides > College Algebra

Why It Matters: The Rectangular Coordinate System and Equations of Lines

Why learn about The Rectangular Coordinate System?

Caroline is a full-time college student planning a spring break vacation. To earn enough money for the trip, she has taken a part-time job at the local bank that pays $15.00/hr, and she opened a savings account with an initial deposit of $400 on January 15. She arranged for direct deposit of her payroll checks. If spring break begins March 20 and the trip will cost approximately $2,500, how many hours will she have to work to earn enough to pay for her vacation? If she can only work 4 hours per day, how many days per week will she have to work? How many weeks will it take? In this section, we will investigate problems like this and others, which generate graphs like the line in the figure below.
Coordinate plane where the x-axis ranges from 0 to 200 in intervals of 20 and the y-axis ranges from 0 to 3,000 in intervals of 500. The x-axis is labeled Hours Worked and the y-axis is labeled Savings Account Balance. A linear function is plotted with a y-intercept of 400 with a slope of 15. A dotted horizontal line extends from the point (0,2500). Figure 1

Learning Objectives

Points and Lines in the Plane
  • Plot ordered pairs, and graph equations by plotting points
  • Use a graphing utility to graph equations
  • Find the x and y intercepts of a graphed equation
  • Use the distance and midpoint formulas

Equations of Lines

  • Write equations of lines in slope-intercept, point-slope, and standard forms
  • Identify the equations and graphs of horizontal and vertical lines
  • Determine whether two lines are parallel, perpendicular, or neither
  • Write equations of lines that are parallel or perpendicular to another line

Licenses & Attributions

CC licensed content, Original

CC licensed content, Shared previously

  • College Algebra. Authored by: OpenStax College Algebra. Located at: https://openstax.org/books/college-algebra/pages/2-2-linear-equations-in-one-variable. License: CC BY: Attribution. License terms: Download for free at http://cnx.org/contents/[email protected].