posted by .

Determine the center and the radius of the following circle:


so I figured I'd use completing the square after putting it in standard form:


I'm not sure where to go from here.

  • pre-calculus -

    but you didn't "complete" the square

    (x^2+8x + 16)+(y^2-2y + 1)= 8 + 16 + 1
    (x+4)^2 + (y-1)^2 = 25

    Now we have it in standard form.
    Can you take it from there ?

  • pre-calculus -

    Ok. Do I take the square root of the whole thing now?

    getting x+4-y-1+-sqrt25

    I've never done this before, I'm not sure if this is even right and if it is, I definitely don't know where to go from here

  • pre-calculus -

    the standard equation of a circle with centre (h,k) and radius r is
    (x-h)^2 + (y-k)^2 = r^2

    so we ended up with
    (x+4)^2 + (y-1)^2 = 25 or
    (x+4)^2 + (y-1)^2 = 5^2

    then the centre is (-4,1) and radius is 5

    Here is an interesting page for your topic

  • pre-calculus -

    Thanks so much for your explanation. I was able to figure it out and now got your answer.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Algebra

    Could you please check some of my Algebra problems please?
  2. Advanced Math

    Write the standard form of the equation of a circle that passes through the points at (0,8) (8,0) and (16,8). Then identify the center and radius of the circle. (x-8)^2 + (y-8)^2 = 64 (x^2 / 64) + (y^2 / 64) = 64 center=(8,8) radius=8 …
  3. Math

    The points (4, –5) and (– 4, 1) are endpoints of a diameter of a circle. (a) Find the center of the circle. (b) Find the length of the radius of the circle. (Note that this is a distance.) Give the exact answer. Show work. (c) …
  4. Pre-Calc

    Determine the center and the radius of the following circle: x^2+y^2+6x-4y-5=0 I got for the radius 3(sqrt2) I got for the center (-3,2) Can you please tell me if I am correct?
  5. Calculus

    Complete the square to write the equation x^2 + y^2 - 6x - 2y + 4 = 0 in standard form. Use the standard form of the equation to identify the center and the radius of the circle.
  6. calculus-can someone please help me with this ques

    I can get part of the answer then I get stumped. find the center and radius of the circle, Write the standard form of the equation. (4,3)(1,3) to get center: (1+4/2, 3+3/2)=5/2,3 answer:5/2,3 for center radius: then i am stuck
  7. pre calculus

    Write the equation of the circle in standard form. Find the center, radius, intercepts, and graph the circle. x^2+y^2-12x-4x+36=0 How on earth do I do this?
  8. college pre-calculus

    4x^2+4y^2-16x-24y+51=0 is the equation of a circle. where is the center of the circle and what is it's radius?
  9. Geometry

    Write the General form equations for the following circles: 1. A circle with center (1, -6) and radius 4 2. A circle with center (6, 8) and radius 10 3. A circle with center (0, 3) and radius 2√3 4. A circle with center (-0.5, 5.5 …
  10. Pre-calculus

    Find the center radius and equation of a circle in standard form given the following conditions: 1. Tangent to 3x+2y=0 at the point (0,0) and passing through (1,-1) and (6,0)

More Similar Questions