The easiest way to solve a cubic equation involves a bit of guesswork and an algorithmic type of process called synthetic division.

That equation has numerous answers because you've got three variables. Instead, find all of the factors of a and d in the equation and then divide the factors of a by the factors of d. Related Content.

Your cubic equation's integer solutions are somewhere in this list. Hence, the invariant we have discovered has an interpretation as one should always expect: Method 3. For this method of finding a cubic equation's solutions, we'll be dealing heavily with the coefficients of the terms in our equation.

Depending on which text editor you're pasting into, you might have to add the italics to the site name. However, if you now go away and try to work out the details of the argument outlined above, you will see that complication is something one should definitely worry about. However, for the expression: If it doesn't, use the quadratic formula to solve it. Following some very general problem-solving techniques has led us to an idea that is definitely new.

How to discover for yourself the solution of the cubic

So how might we make the above calculations manageable? The square root of -3 is equal to "i" multiplied by the square root of 3, or 1. However, the method for solving cubics has actually existed for centuries!

Thanks for letting us know. If you don't want to spend the time plugging in values one by one, try a quicker method that involves a technique called synthetic division. A cubic function is a third-degree polynomial.

Solving Cubic Equations

What would be the natural generalization to cubics of the process of completing the square? What matters is not the difficulty of the problem itself but the difficulty of the difference between the problem and other problems whose solutions are known.

I have put in the factor 2 just for convenience - of course it makes no difference mathematically. This can be accomplished using synthetic division. A cubic equation always has at least one real solution, because the graph will always cross the x -axis at least once. I shall answer this question by yet another time-honoured method, which occurs all over mathematics. A discriminant is simply a number that gives us information about the roots of a polynomial you may already unconsciously know the quadratic discriminant: