In Example 6, change the coefficient of x² to 25.

Data from Example 6

Graphically solve the system of equations:

Solving the first equation for y, we have

Because this is an ellipse, as shown in Example 3, its domain extends from x = −2 to x = 2 (9x² cannot be greater than 36). The exponential curve cannot be negative and increases rapidly, as discussed in Chapter 13. This means we need only graph the upper part of the ellipse (using the + sign). Therefore, we choose the window settings as shown in the calculator display in Fig. 14.7. Using the intersection feature, we find the approximate solutions of x = −2.00, y = 0.11 and x = 0.90, y = 2.68.

9x + 4y 36 y = 3x