Write using exponents. 5 5 5 b b b b

5 to the 3rd power and b to the 4th power, so 5^3 and b^4

Well the answer isn't 20 characters long so i gotta write something but here it is: 5^3 b^4 

X^2 - 4x +(4/2^2) + y^2 + 8y + (8/2^2) = -4 + (4/2^2) + (8/2^2)(x + 2)^2 + (y + 4)^2 = -4 + 4 + 16your center is (-2, -4) and the radius is the sqrt of -4 + 4 + 16 which is 4