Find the domain and the range of the function if f x x?

Given: f(x)=3x^2+6x-2 To find x: x= -b/2a x= -6/2(3) x= -1 to find y, replace x with -1: f(-1)=3(-1)^2+6(-1)-2 y=3(1)-6-2 y= -5