$$f(x)=\frac{(2x)^{1}(x^{2}-36)-(2x)(x^{2}-36)^{2}}{(x^{2}-936)^{2}}=\frac{2}{4x}$$
$fx=-\frac{2x\left(x^{2}-37\right)\left(x^{2}-36\right)}{\left(x^{2}-936\right)^{2}}\text{ and }-\frac{2x\left(x^{2}-37\right)\left(x^{2}-36\right)}{\left(x^{2}-936\right)^{2}}=\frac{2}{3}$
$f=-\frac{2\left(x^{2}-37\right)\left(x^{2}-36\right)}{\left(x^{2}-936\right)^{2}}$
$|x|\neq 6\sqrt{26}\text{ and }\frac{x\left(-x^{4}+73x^{2}-1332\right)}{\left(x^{2}-936\right)^{2}}=\frac{1}{3}$
