Derivative question using the Quotient rule

Ithe problem is as follows: d/dx[1-5x/1+5x] I need to find f'(x) and f''(x)

I found f'(x) but the second derivative is giving me problems. Here is what I did for both: d/dx[1-5x/1+5x] = (1+5x) d/dx [1-5x] - (1-5x) d/dx [1+5x] and all this is divided by (1+5x)^2

= (1+5x)(-5) - (1-5x)(5)/(1+5x)^2 =

-5 -25x - 5 + 25x/(1+5x)^2 =

-10/(1-5x) Now I tried to get f''(x) unsuccessfully I might add.

(1+10x+25x^2) d/dx [-10] - (-10) d/dx [1+10x+25x^2] all this is divided by

(1+10x+25x^2)^2 =

1+10x+25x^2 - (-10)(10)(50x)/(1+10x+25x^2)^2 =

1+5010x+25x^2/(1+10x+25x^2)^2

Please let me know where I went off track.

THANK YOU!

Keith