Question

Can someone please check my answers ?? i will fan and medal(:

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

Answer 1

(X-h)^2 + (y - K)^2 = r^2
(x^2 + 2x + 1) + (y^2 + 2(2y) +4) = 20 + 1 + 4 (perfect squares)
Next step is easy: you compare
(x+1)^2 + (y+2)^2 = 5^2
with the standard form of the circle with centre (h,k) and radius r
(x-h)^2+(y-k)^2 = r^2
and decide what the values of h, k and r are.
From (y+2) = y-k, subtract y from both sides, so
y-y+2 = y-y-k or 2=-k,
multiply by -1 to get -2=k, so we have
h=-1, k=-2, and r=5

From the standard equation of a circle,
(x-h)^2+(y-k)^2=r^2
we therefore found center = (h,k)=-1,-2, and radius = r =5

Answer 2

@zepdrix @jim_thompson5910

Answer 3

I think you meant to say

center = (-1,-2)

Answer 4

if so, you have the correct answer

Answer 5

yeah i did my bad , but is everything in the right order and everything ? and seem correct @jim_thompson5910

Answer 6

everything else looks perfect. Nice work

Answer 7

Thank you!

Answer 8

you're welcome

Answer 9

Thank you!