OBJECTIVES & STANDARDS
Math Objectives
Graph systems of linear equations in slope-intercept form
Identify solutions to systems of linear equations graphically
Determine whether a system of linear equations has one solution, no solutions, or infinite solutions
Common Core Math Standards
Link to all CCSS Math
Personal Finance Objectives
Compare different savings rates over time and how they impact the achievement of savings goals.
National Standards for Personal Financial Education
Saving
2a: Select a preferred location for a savings account based on comparison of interest rates and fees at different types of financial institutions.
DISTRIBUTION & PLANNING
Distribute to students
OBJECTIVES & STANDARDS
Math Objectives
Graph systems of linear equations in slope-intercept form
Identify solutions to systems of linear equations graphically
Determine whether a system of linear equations has one solution, no solutions, or infinite solutions
Common Core Math Standards
Link to all CCSS Math
Personal Finance Objectives
Compare different savings rates over time and how they impact the achievement of savings goals.
National Standards for Personal Financial Education
Saving
2a: Select a preferred location for a savings account based on comparison of interest rates and fees at different types of financial institutions.
DISTRIBUTION & PLANNING
Distribute to students
DESMOS: Systems of Two Linear Equations
Linked in Google Classroom, after completing answer the following question.
What did you learn from this activity?
Systems of Equations
In the last activity, you began exploring how to find a solution that works for two different linear functions. This is called a system of equations.
A system of equations is when two or more equations share the same variables. A solution to that system has to be true for all the equations, not just one. Think back to the last activity when we graphed two lines on the same coordinate plane. The green line represents the number pairs that had a difference of 8. The purple line represents the number pairs with a sum of 1.
How can you test if that point is a solution to both equations in the system?
How could you identify that a system has no solutions, based on the equations in that system?
How could you identify if a system has infinite solutions algebraically?
Could there be a system of linear equations with exactly two solutions? Why or why not?
Part I: Writing Equations
John and Brenda both recently graduated from Hightower University and started jobs as civil engineers at BuildIt Construction company.
Write an equation that represents John’s savings account balance, y, after x months.
Write an equation that represents Brenda’s savings account balance, y, after x months.
Your friend Brian looks at this problem and says “You don’t have to bother graphing this, there’s no solution. John and Brenda both save 20% of their income each month, which means their lines will have the same slope. If you graph them, they’ll be parallel.” Is Brian correct? Why or why not?
Part II: Graphing
Complete the first two equations in the Desmos interactive using your equations from part 1. Do not close this page, you will continue using the graph to answer the following questions.
Fill in the table below from the information provided on the Left.
Read the graph below and note each initial balance on the graph.
Part II: Building an Emergency Fund
Using the Family Budget Calculator, search for your county or closest major city. For each family, input the number of adults and children to find out the monthly income they would need in order to attain a modest yet adequate standard of living. Then, complete the first row of the table in question #15.
Bonus Points: A common rule of thumb is to save up an emergency fund that could cover 3 months of living expenses. Complete the second row to show how much each family would need to save.
Bonus Points: How many weeks would each family need to save in order to build an emergency fund that covered 3 months of living expenses?
Bonus Points: Which family would take the longest to build up that emergency fund? How might they adjust their approach to savings?
Graph both equations in Desmos and Screen Shot in Show your Work below.
Is there a point where all three families have the same amount in savings? Why or why not?