Muḥammad ibn Mūsā al-Khwārizmī mathematics |

## Algebra

Considering only positive numbers,
al-Khwārizmī divided linear and quadratic equations
into six basic types and showed how to solve them.
Although his book was likely a compendium
of existing knowledge, it stands as the first work
to feature a strictly algebraic mathematical approach
so that Latin translations of it in the 12th century
introduced to the West not only the math but the terms
*algebra* and, based on al-Khwārizmī’s name, *algorithm.*

## Operations

The *al-ğabr* operation
is moving a negative quantity on one side of the equation
to a positive quantity on the other side.
This restores negative quantities
which Islamic mathematicians
at the time
did not find useful.
The *al-Muqabala* operation
is subtracting the same positive quantity from both sides.
This balancing or corresponding act
reduces the equation to the fewest terms.

## Variable unknown

Let *x* be an unknown quantity
of a variable thing,
unlike the *E* in *E* = *m**c*^{2}.
When I say *x,* I mean
anything that’s consistent,
not necessarily energy.
Let *x* = *f(y),* where
*f* is an arbitrary function
that depends on a variable *y.*
Our function could return an interest,
the return on a bond,
or the percentage of profit.
In fact, it could be
any useful operation, anything
that’s smart and practical.
Now, indeed, we
are moving to a higher order
of math and intellect.

Unfamiliarity with the notation can make a person feel as though a mathematical topic is beyond their intellectual powers when it is not.

See also in

The book of science:Zero—BrahmaguptaNumber system—Leonardo Pisano Bigollo (Fibonacci)Readings in wikipedia:

The Compendious Book on Calculation by Completion and Balancing”