(y+1)^2/4 - (x-2)^2/16 = 1

so i know how to graph it....

i know the center is (-1,2)

Am I right the to say the a-value is 2 or is it +and- 2

and the b-value is 4 or is it +and- 4

and finally how do you find the domain and range?

is the range 0 less than or equal to y greater than or equal 4

and the domain all real?