ANSWER
The y-intercept is 
[tex](0,1)[/tex]
EXPLANATION
The given polynomial function is 
[tex]f(x) =  -  {x}^{3}  + 3 {x}^{2}  + 1[/tex]
At y-intercept the value of x is zero.
Therefore we need to put 
[tex]x = 0[/tex]
into the given polynomial function to determine the corresponding y-value.
[tex]f(0) =  -  {(0)}^{3}  + 3 {(0)}^{2}  + 1[/tex]
This will give us,
[tex]f(0) =  0 + 0+ 1[/tex]
We further simplify to obtain,
[tex]f(0) =1[/tex]
This means that when 
[tex]x = 0[/tex]
the value of the function is 
[tex]1[/tex]
Hence the y-intercept is 
[tex](0,1)[/tex]