x+2y=12

Question

find intercept
a circle equation x^2+y^2+4x-4y-1=0 and graph
2)find domain and range f(x)=x^2-4x-5
find vertex of f(x) =x^2+4x-21

Answer 1

(12,0) and (0,6)
center at (-2,2) radius 3
domain all reals, range all reals >= -9
(-2,-25)