Home equity: When you purchase a home by securing a mortgage, the total paid toward the principal is your equity in the home. The graph in Figure 1.50 shows for a certain 30-year mortgage the equity,...

Home equity: When you purchase a home by securing a mortgage, the total paid toward the principal is your equity in the home. The graph in Figure 1.50 shows for a certain 30-year mortgage the equity, in dollars, accrued after a given number of monthly payments.

a. Is the graph concave up or concave down?

 b. The graph is increasing. What does the concavity you identified in part a say about how the equity grows?

 c. Use the graph to estimate the amount of the mortgage.