Graphically
Finding Solutions
Example 2
What are the zeros of this polynomial function, P(x) = -x4 - 3x3 + 6x2 + 8x?
Step 1. Estimate the x-intercepts of the graph.
It appears that the zeros of the function are x = -4, x = -1, x = 0, and x = 2.
Step 2. Check the estimates by substituting into the equation.
Because the point is (-4, 0), x = -4 is an x-intercept, or zero, of the equation.
Check the remaining values to ensure accuracy.
The zeros of the function are x = -4, x = -1, x = 0, and x = 2.