Question

How do you write the equation `x^2-4x+y^2+10y=-25` in standard form and find the center and radius?

Answer 1

`(x-2)^2+(y+5)^2= 4`
centre (2,-5)
radius = 2

Explanation:

Completing the square
`x^2-4x+4+y^2+10y+25=-25+25+4`
Remember, whatever you do on one side you also do on the other side
`(x-2)^2+(y+5)^2= 4`
which is in the general form: `(x-h)^2+(y-k)^2=r^2`
so your radius is r and your centre is (h,k)

centre (2,-5)
radius = 2