As $a \in\left\{ 1,2,3 \right\}~~$ is held, can I write $f(a=1)=k~~$ rather than $\text{As}~a=1, f(a)=f(1)=k~~$? $$  x \in\left\{1,2,3\right\}  $$
$$  f(x):=\text{function which returns certain value depending on argument }x $$
Assume the below statements .
$$ \text{As }x=1 ~,~  $$
$$  f(x)=f(1)=k $$
Can I write it as the below notation?
$$  f(x=1)=k $$
I want to know whether teachers subtract of scores or not as the above notation.
The purpose to write as my way is just I want to save the time.
I think that you want to underline the fact that $f$ Is a function on $x$ and that if $x=1$ $f(1)=k$, I Would writer $f(x)|_{x=1}$
I think that you want to underline the fact that $f$ Is a function on $x$ and that if $x=1$ $f(1)=k$, I Would writer $f(x)|_{x=1}$