IM Alg1.2.23 Lesson: Solving Problems with Inequalities in Two Variables
Use graphing technology to graph the solution region of each inequality and sketch each graph.
y>x
y≥x
y<-8
-x+8≤y
y<10x-200
2x+3y>60
Here are three situations.
There are two questions about each situation. For each question that you work on:
Bank Accounts
A customer opens a checking account and a savings account at a bank. They will deposit a maximum of $600, some in the checking account and some in the savings account. (They might not deposit all of it and keep some of the money as cash.)
If the customer deposits $200 in their checking account, what can you say about the amount they deposit in their savings account?
The bank requires a minimum balance of $50 in the savings account. It does not matter how much money is kept in the checking account. If the customer deposits no money in the checking account but is able to maintain both accounts without penalty, what can you say about the amount deposited in the savings account?
Concert Tickets Two kinds of tickets to an outdoor concert were sold: lawn tickets and seat tickets. Fewer than 400 tickets in total were sold. If you know that exactly 100 lawn tickets were sold, what can you say about the number of seat tickets?
Lawn tickets cost $30 each and seat tickets cost $50 each. The organizers want to make at least $14,000 from ticket sales. If you know that exactly 200 seat tickets were sold, what can you say about the number of lawn tickets?
Advertising Packages An advertising agency offers two packages for small businesses who need advertising services. A basic package includes only design services. A premium package includes design and promotion. The agency's goal is to sell at least 60 packages in total. If the agency sells exactly 45 basic packages, what can you say about the number of premium packages it needs to sell to meet its goal?
The basic advertising package has a value of $1,000 and the premium package has a value of $2,500. The goal of the agency is to sell more than $60,000 worth of small-business advertising packages. If you know that exactly 10 premium packages were sold, what can you say about the number of basic packages the agency needs to sell to meet its goal?
This activity will require a partner.
Without letting your partner see it, write an equation of a line so that both the -intercept and the -intercept are each between -3 and 3. Graph your equation on one of the coordinate systems.
Your Inequality
Still without letting your partner see it, write an inequality for which your equation is the related equation. In other words, your line should be the boundary between solutions and non-solutions. Shade the solutions on your graph.
Take turns stating coordinates of points. Your partner will tell you whether your guess is a solution to their inequality. After each partner has stated a point, each may guess what the other’s inequality is. If neither guesses correctly, play continues. Use the other coordinate system below to keep track of your guesses.