(a) Find the slope of the tangent line to the curve $y=1+x+x^{2}$ at the point where $x=a$.

(b-d) Find the slopes of the tangent lines at the points whose x-coordinates are:

  (b) $-8$, (c) $-1/3$, and (d) $2$.

(a)

(b)

(c)

(d)