Consider the graph of the function $f(x)=e^x - 4 x$

A. What is the y-intercept of the graph? $y$ =

B. How many x-intercepts are there? There are x-intercepts

For the following question, enter all possible values, separated by commas. If there are none, type 'none'.

C. At what values of $x$ does the graph have a vertical asymptote? $x$ =

D. What is the equation of the slant asymptote with the highest slope? $y$ =

For the following 2 questions, enter your answers in the form (-2, 3], (-I,0)U[1,2), etc. using I for $\infty$ or type 'empty' for $\emptyset$

E. For what values of $x$ is $f$ decreasing?

F. For what values of $x$ is $f$ concave up?