[tex]\Large\boxed{\begin{array}{l}\sf f(x)=-x^2+4x-3\\\sf f(4)=-4^2+4\cdot4-3\\\sf f(4)=-4+16-3\\\sf f(4)=9\\\sf f(5)= -5^2+4\cdot5-3\\\sf f(5)=-25+20-3\\\sf f(5)=-8\end{array}}[/tex]
