Page:The Algebra of Mohammed Ben Musa (1831).djvu/199

 الكافية في اصول الجبر والمقابلة or “A complete introduction to the elements of algebra.”

باب تفسير الجبر والمقابلة. اعلم ان الحساب انما سموا هذا النوع جبرا لانهم وضعوه علي معادلة فلما كانوا وضعوه علي المعادلة اداهم العمل في اكثر مسائلة الي معادلة الناقص بغير الناقص فلم يكن بد من جبر ذلك الناقص بما ينقص وزيادة مثل ذلك علي ما عدله فلما كثر ذلك فيه سموه جبرا فهذا معني الجبر وعلة تسميتهم به هذا النوع. فاما المقابلة فهو حذف المقادير المتشابهة من الجهتين.

“On the original meaning of the words jebr and mokābalah. This species of calculation is called jebr (or completion) because the question is first brought to an equation And as, after the equation has been formed, the practice leads in most instances to equalize something defective with what is not defective, that defective quantity must be completed where it is defective; and an addition of the same amount must be made to what is equalized to it. As this operation is frequently employed (in this kind of calculation), it has been called jebr: such is the original meaning of this word, and such the reason why it has been applied to this kind of calculation. Mokābalah is the removal of equal magnitudes on both sides (of the equation).”

4. In the Kholāset al Hisāb, a compendium of arithmetic and geometry by Baha' al-din al-'Amili (died 1031, i. e. 1575 ) the Arabic