Question

Using the following equation, find the center and radius of the circle. You must show all work and calculations to receive credit.
x2 + 2x + y2 + 4y = 20

Help me please I will give a medal and fan!!

Answer 1

So far i have this
x2 + 2x + y2 + 4y = 20
(x2 + 2x) + (y2 + 4y) = 20

Answer 2

H!!

Answer 3

The radius is r = sqrt(25) = 5

Answer 4

complete mr square twice, once for each term

Answer 5

I need help figuring it out though, i have no idea whatsoever ho to do this problem.

Answer 6

@dan815 @Michele_Laino

Answer 7

Can someone walk me through this please?

Answer 8

for each to complete the square, take the coefficient on the linear x, y term and add to that quantity half of its square

Answer 9

I honestly have no idea how to do that..

Answer 10

So do i have to figure out that equation? I honestly dont think ill be able to learn this, ive been trying for about an hour

Answer 11

(x^2 + 2x + 1^2 ) + (y^2 + 4y + 2^2) = 20 + 1^2 + 2^2

you take half the middle term and add the square of it , now you can do this

(x+1)^2 + (y+2)^2 = 25

Answer 12

http://www.mathsisfun.com/algebra/completing-square.html

Answer 13

the center of a circle in that form is

(x - h)^2 + (y - k)^2 = r^2

here C(h,k) = C(-1 , -2) and r is the square root of 25

Answer 14

so the radius is 25 and the center of the circle is 5?

Answer 15

since 5 is the square root of 25

Answer 16

the center is the point (h,k) or ( -1 , -2),, how far each point on the circle is away from that center; the radius, is the square root of 25, or 5

Answer 17

r^2 = 25 r = 5

Answer 18

i am so confused.....

Answer 19

after you complete the squares, you have an equation in the form of ...

(x-h)^2 + (y-k)^2 = r^2

r= radius, and (h,k) = the center point