Mathematics - Functions Question with Solution | TestHub

We have been given that

$f\left(g\left(x\right)\right)=x+3-\sqrt{x}$

$\Rightarrow f(\sqrt{x}+1)=x+3-\sqrt{x}$

Put $\sqrt{x}+1=t$

$\sqrt{x}=t-1$

$x=(t-1{)}^2$

$\Rightarrow f\left(t\right)=(t-1{)}^2+3-(t-1)$

$\Rightarrow f\left(0\right)=1+3+1=5$

Hence this is the correct option.