Very nice work!
[MATH]\frac{1}{a^2}+\frac{1}{a^2x^2}+\frac{1}{a^2(x+1)^2}\\ =\dfrac{1}{a^2}\left(1+\dfrac{1}{x^2}+\dfrac{1}{(x+1)^2}\right)\\ =\dfrac{1}{\big(ax(x+1)\big)^2}\big(\big(x(x+1)\big)^2+(x+1)^2+x^2\big)\\ =\dfrac{1}{\big(ax(x+1)\big)^2}\big(\big(x(x+1)\big)^2+2x(x+1)+1\big)\\ =\dfrac{1}{\big(ax(x+1)\big)^2}\big(x(x+1)+1\big)^2[/MATH]
[MATH]\frac{1}{a^2}+\frac{1}{a^2x^2}+\frac{1}{a^2(x+1)^2}\\ =\dfrac{1}{a^2}\left(1+\dfrac{1}{x^2}+\dfrac{1}{(x+1)^2}\right)\\ =\dfrac{1}{\big(ax(x+1)\big)^2}\big(\big(x(x+1)\big)^2+(x+1)^2+x^2\big)\\ =\dfrac{1}{\big(ax(x+1)\big)^2}\big(\big(x(x+1)\big)^2+2x(x+1)+1\big)\\ =\dfrac{1}{\big(ax(x+1)\big)^2}\big(x(x+1)+1\big)^2[/MATH]