Explanation:
The rational expression is given by:
[tex]E=\frac{2x^2-72}{5x^2-245} \\ \\ Factor \ out: \\ \\ E=\frac{2(x^2-36)}{5(x^2-49)} \\ \\ E=\frac{2(x-6)(x+36)}{5(x-7)(x+7)} : \ \ \ \ a^2-b^2=(a-b)(a+b)[/tex]
The denominator can't be zero, therefore:
[tex](x-7)(x+7)\neq 0 \\ \\ \\ Thus: \\ \\ \boxed{x\neq 7 \ and x \neq -7}[/tex]
Finally, the values of x that make the rational expression undefined are
x = 7 and x = -7
