Expand the brackets (x+1)(x-4)

When we are presented with a quadratic equation in this form, and asked to expand, it is important to make sure that every term is used. For example, we would begin with the 'x' from the (x+1) bracket, and then multiply this by the 'x' in the (x-4) bracket, and the '-4' in the (x-4) bracket. That will give us x^2 -4x. Next, we take the '+1' from the (x+1) bracket and multiply this by both terms in the (x-4) bracket, giving us x-4. Now, all we need to do is collect like terms, and present our expanded quadratic equation in the simplest way. So overall we have x^2 -4x +x -4. This simplifies to x^2 -3x -4, which is the expansion which we require.