Answer:
x = - 4
Explanation:
f(x) =

the denominator cannot be zero as this would make f(x) undefined.
Equating the denominator to zero and solving gives the value that x cannot be and if the numerator is non zero for this value then it is a vertical asymptote.
x + 4 = 0 ( subtract 4 from both sides )
x = - 4 ← excluded value
2x² - 8 = 2(- 4)² - 8 = 32 - 8 = 24 ← non zero numerator
then x = - 4 is the vertical asymptote of f(x)