The Handy Math Answer Book

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What is the discriminantof a quadratic equation?

In the quadratic equation ax^2 bxc0, the value of b^2  4 acis the discrimi-

nant—the same numbers and letters that are under the square root sign of the qua-

dratic formula. This is actually the products of the squares of the polynomial root dif-

ferences. In other words, this quantity characterizes certain properties of the

quantity’s roots. The discriminant is often used for such mathematical concepts as

metrics, modules, quadratic fields, and polynomials.

MORE ALGEBRA

What is an array?

A mathematical array is a list of lists, or a rectangular arrangement of objects; it is a

useful way of keeping a collection of things. Arrays are orderly arrangements of objects

in columns and rows, with the objects most often being numbers. For example, the

most common arrays are two-dimensional with a certain amount of rows and columns:

In this case, this is a 2-by-3 array (rows are always mentioned before columns).

The order of numbers and/or elements in an array may sometimes, but not always, be

significant (as it is in a matrix; see below).

What is a matrix?

A matrix is a concise way of representing and working with linear transformations; also, it

is a rectangular array or grid of numbers or variables that allows the user to perform cer-

tain mathematical operations. They are usually symbolized as large parentheses or two

large pair of parallel double lines surrounding the array of numbers or variables. These

numbers can be manipulated to solve systems of equations or problems with many differ-

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