Is there a method to find a math expression for a given pattern? I have this pattern and I am very curious to find out how can I generate it.
3 -4x 3x^2
5 -9x 9x^2 -5x^3
7 -16x 21.6x^2 -16x^3 7x^4
9 -25x 42.86x^2 -42.86x^3 25x^4 -9x^5
11 -36x 75x^2 -95.24x^3 75x^4 -36x^5 11x^6