Flos/Problems/Problem 2

Problem from by

 * Solve the cubic:
 * $x^3 + 2 x^2 + 10 x = 20$

Solution

 * $1 \cdotp 3688081075 \dots$

Proof
Express the equation as:
 * $x^3 + 2 x^2 + 10 x - 20 = 0$

We apply Cardano's Formula, with $a = 1$, $b = 2$, $c = 10$ and $d = -20$.

Thus:

Then:

The other two roots are complex.