How do I solve this equation : 36x^3-100x=0

You can solve this equation by first factoring out the leading coefficient, which is 36. In other words, you can divide every term on both sides of the equation by 36. After that, you can factor the polynomial on the left-hand side of the equation such that it becomes a quadratic, and you divide both sides of the equation by the value that you factored out. You should be left with a quadratic now, and you can solve for x by taking the square root, completing the square or using the quadratic formula.