Answer
$y(x)=-e^x$
Work Step by Step
Observe that the graph is of the form $y=-b^x$. To find the equation of the graph, we need to find the value of $b$. To find this value, we substitute values from the point $(1,-e)$. We get $b=e$. Thus the equation is $y(x)=-e^x$.
$y=b^x\rightarrow-e=-b^1\rightarrow{b}=e$
$y(x)=-e^x$