Question 480798
{{{(9-x^-2) / (3 + x^-1)=(9-1/x^2) / (3 +1/ x)=((9x^2-1)/x^2)/((3x+1)/x)=((9x^2-1)x)/(x^2(3x+1))=((3x-1)(3x+1))/(x(3x-1))=(3x+1)/x}}}
Use formula {{{a^2-b^2=(a-b)(a+b)}}}
{{{9x^2-1=(3x)^2-1^2=(3x-1)(3x+1)}}}