If the value is:
\(\sf{\frac{2}{a+8}}\)
Then it will be undefined when the denominator is equal to 0.
So set the denominator equal to 0
a + 8 = 0
a = -8
So when
\(\huge{\boxed{\bf{a=-8}}}\)
then the value will be undefined.
Just a note:
\(\sf{\frac{x}{0}=}\) undefined
\(\sf{\frac{0}{x}=0}\)
