How to factor cubic trinomials? x^3-7x-6
2 Answers
Explanation:
You could solve this by plotting the equation and inspecting where the roots are:
graph{x^3-7x-6 [-5, 5, -15, 5]}
We can see there appear to be roots in the areas of
Use the rational roots theorem to find possible roots, try each to find roots
Explanation:
Find roots of
Any rational root of a polynomial equation in standard form is of the form
In our case
So the only possible rational roots are:
Let
So
Divide
Actually you can deduce the
So the complete factorisation is: