A circle is represented by the equation x2+y2−10x+4y=−13 . Complete the square to discover the center and the radius of the circle. Type your answers in as numeral numbers only. Make sure to include the negative sign, if needed.

1 answer

To complete the square for the equation of the circle \(x^2 + y^2 - 10x + 4y = -13\), we start by rearranging it:

  1. Rearrange the equation: \[ x^2 - 10x + y^2 + 4y = -13 \]

  2. Complete the square for the \(x\) terms:

    • Take the coefficient of \(x\), which is \(-10\), halve it to get \(-5\), and square it to get \(25\).
    • Add and subtract \(25\) to the equation.
  3. Complete the square for the \(y\) terms:

    • Take the coefficient of \(y\), which is \(4\), halve it to get \(2\), and square it to get \(4\).
    • Add and subtract \(4\) to the equation.

Now, the equation becomes: \[ (x^2 - 10x + 25) + (y^2 + 4y + 4) = -13 + 25 + 4 \]

This simplifies to: \[ (x - 5)^2 + (y + 2)^2 = 16 \]

Now, we can identify the center and the radius:

  • The center of the circle is \((5, -2)\).
  • The radius is \(\sqrt{16} = 4\).

Thus, the answers are:

  • Center: \(5, -2\)
  • Radius: \(4\)

So, the final answer is: Center: 5, -2; Radius: 4