reduceByAsir

 [[f g] v] reduceByAsir [ff gg]   (ox_asir function)
 [[f g]] reduceByAsir [ff gg]  
Example 1: [[(2 x -2) (4 x - 8)] (x)] reduceByAsir 
Note that there may be a gcd that is more than 1 among the coefficients.