 In the 15th century, Luca Patioli was trying to find a general solution to cubic equations. He finally gave up, in 1494. A solution was eventually found by Gerolemo Cardano, however he came across a few equations that could not be solved as they involved the square roots of minus numbers. He assumed that this was Matt's way of saying that no solution existed, but then in 1572 Ruffa Elbomberli found he could solve those last few equations by viewing those pesky square roots not as part of the solution, but simply as a step along the way and arranging the problem so that in the solution they cancelled out. However, for the next 200 years the square root of minus 1 was treated with suspicion by mathematicians. René Descartes even called them imaginary numbers. It was Leonhard Euler who finally convinced the world that imaginary numbers existed when he used them in his famous formula in 1748.