Answer
$0$
Work Step by Step
$\lim _{x\rightarrow 0}\dfrac {\sqrt {25-x^{2}}-5}{x}=\dfrac {\dfrac {d}{dx}\left( \sqrt {25-x^{2}}-5\right) }{\dfrac {d}{dx}\left( x\right) }=\dfrac {\dfrac {1}{2\sqrt {25-x^{2}}}\times \left( -2x\right) }{1}=-\dfrac {x}{\sqrt {25-x^{2}}}=-\dfrac {0}{\sqrt {25-0}}=0$
