Hi! Thanks for helping me!

Show that the equation x^3 - x^2 +x - 21 = 0 has only one solution.

and

Without dividing find the remainder when x^3 - 4x + 12x - 2 is divided by x+1.

and one more

For what values of k does the graph of y = 2x^2 - kx + 3 have a TP on the x-axis?

Thanks for your great help!