In each of the following Exercises 10 to 20, find the equation for the ellipse that satisfies the given conditions: Foci (± 3, 0), a = 4
The equation of the ellipse is x²/16 + y²/7 = 1.
Explanation
This question tests understanding of ellipse parameters. Since the foci are at (±3, 0) on the x-axis, the major axis lies along the x-axis, and the standard form x²/a² + y²/b² = 1 applies. Given c = 3 and a = 4, students must apply the fundamental relationship c² = a² - b² to find b² = 7.
Solution Steps
Step 1: Since foci are at (±3, 0) on the x-axis, the major axis is along the x-axis. So the equation is of the form x²/a² + y²/b² = 1.
Step 2: Given c = 3 and a = 4.
Step 3: Using the relation c² = a² - b², we get 9 = 16 - b².
Step 4: Therefore, b² = 16 - 9 = 7.
Step 5: Hence, the equation of the ellipse is x²/16 + y²/7 = 1.