You are given the function
[tex]f(x)=\dfrac{3}{x+2}-\sqrt{x-3}.[/tex]
To find f(19) you have to substitute 19 instead of x in previous expression:
[tex]f(19)=\dfrac{3}{19+2}-\sqrt{19-3}=\dfrac{3}{21}-\sqrt{16}=\dfrac{1}{7}-4=\dfrac{1-4\cdot 7}{7}=\dfrac{-27}{7}.[/tex]
Answer: [tex]f(19)=-\dfrac{27}{7}.[/tex]
