What is a sign chart?
Please see below.
Sign chart is used to solve inequalities relating to polynomials, which can be factorized into linear binomials. For example, of the type
It could also be less than or less than or equal or greater than or equal, but the process is not much effected.
Note that these can be written as
Note that numbers
For example, if they are already in increasing order, these are
In these intervals, we can find that each of these linear binomial i.e.
and hence the polynomial (as it is a product of these linear binomials) will take positive or negative value
and can easily check the intervals, where the inequality is satisfied, giving us the result.
As an example, one may like to see solution to this question. .