Question

Use the x-intercept method to find all real solutions of the equation. x^3-9x^2+11x+21=0

Answer 1

We must graph y=x^3-9x^2+11x+21. Please, see the attached file.
Then we see were the graph cuts the x-axis, and these values of x are the real solutions of the given equation:

The real solutions of the given equation are:x = -1, 3, and 7