How do you find all the zeros of #f(x)=x^3 -8x^2 -23x +30#?
To solve a cubic equation it exists the solving formula but it is very long and I do not know it.
Then I use a bit of luck to solve this equation. For example I see that
Then I know that the equation has to be in the form
Comparing this with our initial equation we see that
Our function is then
Now we have to solve a second order equation
that has the two solutions
Then the function
can be rewritten as