a) To solve the equation x^2 - 4x = 0, we can factor out an x: x(x - 4) = 0. This equation is satisfied when either x = 0 or x - 4 = 0. Therefore, the solutions are x = 0 and x = 4.

b) To solve the equation 2x^2 - 5x = 0, we can factor out an x: x(2x - 5) = 0. This equation is satisfied when either x = 0 or 2x - 5 = 0. Solving the second equation, we find x = 5/2. Therefore, the solutions are x = 0 and x = 5/2.

c) To solve the equation 4x^3 - x = 0, we can factor out an x: x(4x^2 - 1) = 0. This equation is satisfied when either x = 0 or 4x^2 - 1 = 0. Solving the second equation, we find x^2 = 1/4. Taking the square root of both sides, we get x = ±1/2. Therefore, the solutions are x = 0, x = 1/2, and x = -1/2.

d) To solve the equation 4x^2 - 36x = 0, we can factor out 4x: 4x(x - 9) = 0. This equation is satisfied when either 4x = 0 or x - 9 = 0. Solving the second equation, we find x = 9. Therefore, the solutions are x = 0 and x = 9.