Subtraction

Subtraction is a mathematical operation that represents the operation of removing objects from a collection. It is signified by the minus sign (−). For example, in the picture on the right, there are 5 − 2 apples—meaning 5 apples with 2 taken away, which is a total of 3 apples. Therefore, 5 − 2 = 3. Besides counting fruits, subtraction can also represent combining other physical and abstract quantities using different kinds of objects including negative numbers, fractions, irrational numbers, vectors, decimals, functions, and matrices.

Subtraction follows several important patterns. It is anticommutative, meaning that changing the order changes the sign of the answer. It is not associative, meaning that when one subtracts more than two numbers, the order in which subtraction is performed matters. Subtraction of 0 does not change a number. Subtraction also obeys predictable rules concerning related operations such as addition and multiplication. All of these rules can be proven, starting with the subtraction of integers and generalizing up through the real numbers and beyond. General binary operations that continue these patterns are studied in abstract algebra.

Arise (Sepultura album)

Arise is the fourth studio album by Brazilian heavy metal band Sepultura, released in 1991 by Roadrunner Records. Upon its release, the album received top reviews from heavy metal magazines such as Rock Hard, Kerrang! and Metal Forces.Arise is considered Sepultura's finest hour among longtime fans. While the music on Arise was mostly in the same death/thrash style as their previous album, Beneath the Remains, it was clear that the Sepultura sound was acquiring an experimental edge.

The album presented their first incursions with industrial music, hardcore punk and Latin percussion. The tour (1991–1992) that supported the album was the group's longest at that time, totalling 220 shows in 39 different countries. During this trek, the album went gold in Indonesia—the band's first music industry certification. By the tour's end, Arise had achieved platinum sales worldwide.

Production

In August 1990, the band travelled to Florida to work on the album. Scott Burns reprised his role as producer and audio engineer, and now with a major advantage: Sepultura were at his home studio, Morrisound, a studio properly equipped to record their music style. Their label Roadrunner granted a $40,000 budget, which helped explain the album's improved production values. That allowed Igor and Burns, for example, to spend a whole week just testing the drum kit's tunings and experimenting with microphone practice.