Cual es el maximo comun divisor entre 12a2 y 9a4

∆red ≅ ∆ by rule will give brainiest if possible

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

How is the equation of this circle written in standard form? x2 + y2 - 6x + 14y = 142 a) (x - 3)2 + (y + 7)2 = 200 b) (x+ 3)2 + (y - 7)2 = 200 (x - 6)2 + (y + 14)2 = 142 d) (x+6)2 + (y- 14)2 = 142