Waar wordt in het dagelijks leven een derdegraadsvergelijking als x3+6x=8 voor gebruikt, oftewel wat heb je aan zo'n vergelijking? En wat is precies de formule van Girolamo Cardano?
Imp
Leerling bovenbouw havo-vwo - woensdag 18 juli 2001
Antwoord
"Negative numbers have not been fully accepted until the 18th century. Gerolamo Cardano (1501-1576) who scorned them as numeri ficti, devoted two separate chapters in his Ars Magna, one to equations in the form x3 + mx = p and another to equations x3 = mx + p."
"Rule to solve x3+mx=n Cube one-third the coefficient of x; add to it the square of one-half the constant of the equation; and take the square root of the whole. You will duplicate this, and to one of the two you add one-half the number you have already squared and from the other you subtract one-half the same... Then, subtracting the cube root of the first from the cube root of the second, the remainder which is left is the value of x (Gerolamo Cardano, Ars Magna, 1545)."