Question

X2 + y2 + 6x − 4y + 12 = 0 need center and equation of the circle

Answer 1

Looks like you got a typo, the equation must be:
`x^2+y^2+6x-4y+12=0`
To solve it:
First, rewrite it in the form of a standard circle equation.

`\left(x-\left(-3\right)\right)^2+\left(y-2\right)^2=1^2`
Then, we know the answer:
The center is found at:
`\left(-3,\:2\right)`

`r=1`

Have a nice day! :)