1. **State the problem:** We need to graph the ellipse given by the equation $$16x^2 + 25y^2 + 64x + 50y - 311 = 0$$ and find its center, axes lengths, and intercepts.
2. **Rewrite the equation grouping x and y terms:**
$$16x^2 + 64x + 25y^2 + 50y = 311$$
3. **Complete the square for x and y terms:**
- For x: factor out 16: $$16(x^2 + 4x)$$
- For y: factor out 25: $$25(y^2 + 2y)$$
4. **Complete the square inside each parenthesis:**
- For $$x^2 + 4x$$, add and subtract $$4$$ (since $$(\frac{4}{2})^2 = 4$$):
$$x^2 + 4x + 4 - 4 = (x+2)^2 - 4$$
- For $$y^2 + 2y$$, add and subtract $$1$$ (since $$(\frac{2}{2})^2 = 1$$):
$$y^2 + 2y + 1 - 1 = (y+1)^2 - 1$$
5. **Substitute back and simplify:**
$$16((x+2)^2 - 4) + 25((y+1)^2 - 1) = 311$$
$$16(x+2)^2 - 64 + 25(y+1)^2 - 25 = 311$$
$$16(x+2)^2 + 25(y+1)^2 = 311 + 64 + 25$$
$$16(x+2)^2 + 25(y+1)^2 = 400$$
6. **Divide both sides by 400 to get the standard ellipse form:**
$$\frac{(x+2)^2}{\frac{400}{16}} + \frac{(y+1)^2}{\frac{400}{25}} = 1$$
$$\frac{(x+2)^2}{25} + \frac{(y+1)^2}{16} = 1$$
7. **Interpret the ellipse parameters:**
- Center: $$(-2, -1)$$
- Semi-major axis $$a = 5$$ (since $$\sqrt{25} = 5$$)
- Semi-minor axis $$b = 4$$ (since $$\sqrt{16} = 4$$)
8. **Summary:** The ellipse is centered at $$(-2, -1)$$ with horizontal semi-major axis length 5 and vertical semi-minor axis length 4.
**Final equation for graphing:**
$$\frac{(x+2)^2}{25} + \frac{(y+1)^2}{16} = 1$$
Ellipse Graph
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