1. **State the problem:** Show that the equation $4x^2 + 4y^2 + 7x - 11y = 0$ represents a circle.
2. **Recall the general form of a circle's equation:**
$$ (x - h)^2 + (y - k)^2 = r^2 $$
where $(h,k)$ is the center and $r$ is the radius.
3. **Rewrite the given equation:**
Divide the entire equation by 4 to simplify:
$$ \cancel{4}x^2 + \cancel{4}y^2 + \frac{7}{4}x - \frac{11}{4}y = \cancel{0} $$
which simplifies to
$$ x^2 + y^2 + \frac{7}{4}x - \frac{11}{4}y = 0 $$
4. **Complete the square for $x$ and $y$ terms:**
Group $x$ and $y$ terms:
$$ (x^2 + \frac{7}{4}x) + (y^2 - \frac{11}{4}y) = 0 $$
For $x$:
Take half of $\frac{7}{4}$, which is $\frac{7}{8}$, and square it:
$$ \left(\frac{7}{8}\right)^2 = \frac{49}{64} $$
For $y$:
Take half of $-\frac{11}{4}$, which is $-\frac{11}{8}$, and square it:
$$ \left(-\frac{11}{8}\right)^2 = \frac{121}{64} $$
Add these squares to both sides:
$$ (x^2 + \frac{7}{4}x + \frac{49}{64}) + (y^2 - \frac{11}{4}y + \frac{121}{64}) = 0 + \frac{49}{64} + \frac{121}{64} $$
5. **Rewrite as perfect squares:**
$$ \left(x + \frac{7}{8}\right)^2 + \left(y - \frac{11}{8}\right)^2 = \frac{170}{64} $$
Simplify the right side:
$$ \frac{170}{64} = \frac{85}{32} $$
6. **Conclusion:**
The equation is now in the form
$$ (x - h)^2 + (y - k)^2 = r^2 $$
with center
$$ \left(-\frac{7}{8}, \frac{11}{8}\right) $$
and radius
$$ r = \sqrt{\frac{85}{32}} $$
Therefore, the given equation represents a circle.
Circle Equation 6B9631
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