Subtract 2/x^2-10x+25 - 4/x-5
you need to find a common denominator (bottom) it is x^2(x-5)
2(x - 5)/[(x^2(x-5)] -[10x(x^2)(x-5)]/[x^2(x-5)] + 25/[x^2(x-5)] -4x^2/[x^2(x-5)]
rewrite with the full top over bottom
2(x-5) - 10x(x^2)(x-5) + 25x^2(x-5) -4x^2 /x^2(x-5)
multiply each term out
2x - 10 -10x^3(x-5) + 25x^3 -125x^2 -4x^2/x^3 -5x^2
2x - 10 -10x^4 -50x^3 + 25x^3 -125x^2 -4x^2/x^3 -5x^2
gather like terms
-10x^4 -25x^3 -129x^2 + 2x -10/x^3 - 5x^2