$25-26$

$($a$)$ Show that $f$ has a removable discontinuity at

$($b$)$ Redefine $f(3)$ so that $f$ is continuous at $x=$ discontinuity is "removed"$).$

$25.f(x)=\frac{x-3}{x^2-9}$

$26.f(x)=\frac{x^2}{?}$