Please answer this

What is the value of the expression below? (81^2)^1/8

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?

Determine the common ratio and find the next three terms of the geometric sequence. 10, 2, 0.4, a. 0.2; -0.4, -2, -10 c. 0.02; 0.08, 0.016, 0.0032 b. 0.02; -0.4, -2, -10 d. 0.2; 0.08, 0.016, 0.0032 select the best answer from the choices provided a b c d