Factorise completely x-4x^3

Take out all common factors, in this case only x. This leaves you with x(1-4x^2).Within the brackets you now have a quadratic equation which you can factorise. You need to find factors of -4x^2 that plus to make times to make 0 and plus to make 1. This leaves you with (1-2x)(1+2x). You then bring the x from before so your final answer is:x(1-2x)(1+2x)