Because the coefficient of the 4th order term of this poly is +1, the graph opens up and increasingly resembles that of y = x^4 as x becomes large without bound.
The zeros (roots) of this polynomial are x=-a, x=b, x=-c and x=d.
Supposing that -a < -c < b < d,
as we move from left to right, the graph descends, crosses the x-axis at x = -a, turns upward and crosses the x-axis again at x = -c, reaches a peak (max), heads downward to cross the x-axis at x = b, reaches a minimum, and then heads upward to cross the x-axis at x = d, producing a "w" shaped graph.
The y-intercept will be y = a(-b)(c)(-d), obtained by letting x=0.
The x-intercepts are (-a,0), (b,0), (-c,0) and (d,0).
