How do you write a polynomial with zeros: -3,1,5,6?

1 Answer
Feb 4, 2016

For a zero, when x has that value the overall bracket (parenthesis) needs to sum to zero. For example (x+3)=(3+3)=0. That means the solution is (x+3)(x1)(x5)(x6).

Explanation:

A 'zero' or 'root' of an equation is a point at which it crosses the x-axis: that is, the line y=0 (or f(x)=0).

For that to happen, one of the factors must go to zero. If we take the example of x=3, we need a factor that, when x has that value, will equal zero. If it's in the form (x+a) and we put in the value x=3, the value of a required is 3.

For a positive value of x such as x=5, the factor needs to be (x5) so that it becomes zero when x=5.

Using this approach, over all we get:

(x+3)(x1)(x5)(x6)

We could multiply this through to get an expression in x4 and all lower values, but it's probably best left in this factorized form.