What transformation will always map a parallelogram onto itself

I'll give brainliest if you answer right : )

If f(x)= 3x+6 which of the following is the inverse of f(x)

What are the values of a, b, and c in the quadratic equation 0 = x2 – 3x - 2? a = 1, b = 3, c = 2 a=, b = -3,c=-2 a = 1, b = 3, c= 2 a = 1.0= -3, c = 2