Page:The Algebra of Mohammed Ben Musa (1831).djvu/211

    distinctly intimates that he derived it from our author, by introducing the problem which immediately follows it, with the words: Nunc autem proponamus quæstiones nostras.

The manuscript has the following marginal note to this passage: هذه المسئلة تعمل بالكعب وطريقه ان تاخذ مالا وتلقي ثلثه يبقي ثلثا مال تضرب ذلك في ثلثة اجذار فيكون كعبين يعدلان مالا فزده مرتين علي قدر المال يكون جذرين يعدلان درهما والجذر نصف المال والمال اذا القيت ثلثه بقي سدس اذا ضربت ذلك في ثلثة اجذاره وهي درهم ونصف بلغ ذلك ربع درهم مثل المال كما ذكر ربع “This instance may also be solved by means of a cube. The computation then is, that you take the square, and remove one-third from it; there remain two-thirds of a square. Multiply this by three roots; you find two cubes equal to one square. Extracting twice the square-root of this, it will be two roots equal to a dirhem. Accordingly one root is one-half, and the square one-fourth. If you remove one-third of this, there remains one-sixth, and if you multiply this by three roots, that is by one dirhem and a half, it amounts to one-fourth of a dirhem, which is the square as he had stated.”