2.10: Integer roots of cubics

The cubic equation $x^{3} + ax^{2} + bx - 40 = 0$ has three positive integer roots. Two of the roots are 2 and 4. Find the other root and the value of each of the integers $a$ and $b$.

Do not use a calculator in this question.

Solve the equation $x^{3} - 5x^{2} - 46x - 40 = 0$ given that it has three integer roots, only one of which is positive.