Math Problem Statement

What is the standard form of the equation? What are the coordinates of the center, the endpoints of the major axis, and the coordinates of the two foci?

Solution

Let's break down and solve the problem based on the equation given in the image:

The given equation is: 144x2+81y2+2016x648y=3312144x^2 + 81y^2 + 2016x - 648y = 3312 This equation describes an ellipse, and we need to solve the questions related to it.

Step 1: Rewrite the equation of the ellipse

We start by grouping the xx and yy terms to complete the square:

144x2+2016x+81y2648y=3312144x^2 + 2016x + 81y^2 - 648y = 3312

Now, factor out the coefficients of x2x^2 and y2y^2 from the grouped terms: 144(x2+14x)+81(y28y)=3312144(x^2 + 14x) + 81(y^2 - 8y) = 3312

Step 2: Complete the square for xx and yy

For x2+14xx^2 + 14x, take half of 14 (which is 7) and square it (49), then add and subtract 49 inside the parentheses:

= 144((x + 7)^2 - 49)$$ Similarly, for $$y^2 - 8y$$, take half of 8 (which is 4) and square it (16), then add and subtract 16 inside the parentheses: $$81(y^2 - 8y + 16 - 16) = 81((y - 4)^2 - 16)$$ ### Step 3: Substitute the completed squares Now substitute these back into the equation: $$144((x + 7)^2 - 49) + 81((y - 4)^2 - 16) = 3312$$ Simplify: $$144(x + 7)^2 - 144 \cdot 49 + 81(y - 4)^2 - 81 \cdot 16 = 3312$$ $$144(x + 7)^2 + 81(y - 4)^2 - 7056 - 1296 = 3312$$ $$144(x + 7)^2 + 81(y - 4)^2 = 3312 + 7056 + 1296$$ $$144(x + 7)^2 + 81(y - 4)^2 = 11664$$ ### Step 4: Divide by 11664 to put in standard form $$\frac{144(x + 7)^2}{11664} + \frac{81(y - 4)^2}{11664} = 1$$ Simplify the fractions: $$\frac{(x + 7)^2}{81} + \frac{(y - 4)^2}{144} = 1$$ This is the standard form of the ellipse equation: $$\frac{(x + 7)^2}{9^2} + \frac{(y - 4)^2}{12^2} = 1$$ ### Answer to Question 5: The standard form is: $$\frac{(x + 7)^2}{9^2} + \frac{(y - 4)^2}{12^2} = 1$$ So, the correct option is **a**. ### Answer to Question 6: The center of the ellipse is at $$(-7, 4)$$, since the equation is in the form $$(x + h)^2/a^2 + (y - k)^2/b^2 = 1$$, where the center is $$(h, k)$$. So, the correct option is **d**. ### Answer to Question 7: The major axis is along the $$y$$-axis because the larger denominator (144) is under the $$y$$-term. The length of the major axis is $$2b = 2 \times 12 = 24$$, so the endpoints are 12 units above and below the center. Thus, the endpoints are at $$(-7, 4 + 12) = (-7, 16)$$ and $$(-7, 4 - 12) = (-7, -8)$$. So, the correct option is **a**. ### Answer to Question 8: The distance between the center and the foci is given by $$c = \sqrt{b^2 - a^2} = \sqrt{144 - 81} = \sqrt{63} \approx 7.94$$. The foci are along the major axis, which is vertical, so the coordinates of the foci are at $$(-7, 4 + 7.94)$$ and $$(-7, 4 - 7.94)$$, approximately $$(-7, 11.94)$$ and $$(-7, -3.94)$$. So, the correct option is **b**. --- Do you want any further details or explanations for these solutions? Here are 5 related questions to consider: 1. How do you find the eccentricity of this ellipse? 2. How does the length of the major axis affect the shape of the ellipse? 3. What would happen if $$a$$ and $$b$$ were equal in an ellipse equation? 4. How can you derive the equation of a hyperbola from an ellipse? 5. Can you graph the equation of this ellipse by hand? **Tip:** To easily spot the center of a conic section like an ellipse, always look for the terms in the form $$(x + h)^2$$ and $$(y - k)^2$$ in the equation.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Ellipse
Standard form
Completing the square
Conic sections

Formulas

(x + h)^2 / a^2 + (y + k)^2 / b^2 = 1 for an ellipse
Distance formula for foci: c = sqrt(b^2 - a^2)

Theorems

Ellipse standard equation theorem
Completing the square method

Suitable Grade Level

Grade 11-12