f(x)=x^3+7x-22 and linear factorization of f(x)

Printable View

- Oct 26th 2008, 07:49 PMgreenpumpkinsFinding Zeros and Linear Factorization
f(x)=x^3+7x-22 and linear factorization of f(x)

- Oct 27th 2008, 12:19 PMHallsofIvy
It is interesting that your title puts "finding zeros" first! Of course a typical way of solving a polynomial equation is to first factor it, but it can be done the other way. By the "rational root theorem", the only possible rational roots to this equation are , , , or , the various factors of 22. By simply putting those numbers into f(x), it is easy to see that the only rational root is x= 2. That tells us that x-2 is a factor. Divide by x- 2 to find the other (quadratic) factor. You can solve that using the quadratic formula and use those roots to find the two other linear factors.