The following equation is given. Complete parts (a)-(c). x-5x-4x+20=0 a. List all rational roots that are possible according to the Rational Zero Theorem. (Use a comma to separate answers as needed.) b. Use synthetic division to test several possible rational roots in order to identify one actual root. One rational root of the given equation is (Simplify your answer.) c. Use the root from part (b) and solve the equation. The solution set of x3 - 5x-4x+20=0 is . (Simplify your answer. Type an exact answer, using radicals as needed. Use integers or fractions for comma to separate answers as needed.)