Answer
$f(t)=t^2$
Work Step by Step
We are given that $x=t-1$
Re-write as: $t=x+1$
When $a$ has a positive value then , shift the function to the right for $a$ units and when $a$ has a negative value then , shift the function to the left for $a$ units
Now, $f(t-1) =(t-1)^2$ and $f(x)=(x+1-1^2 =x^2$
So, we have: $f(t)=t^2$