constant
A number is said to be a constant if it has the same value under all conditions. For example, in the formula:
(area of a circle) = π × (radius)²,
π is a constant, equal to 3.14159 ...,
applying equally well to all circles.
infinity
Mathematics recognizes several kinds of infinity. One of them occurs when numbers become very large. For example, the quotient of 12 divided by a number x, as x becomes closer and closer to 0, becomes indefinitely large, and the limit is called infinity and is denoted ∞.
equation, simultaneous, linear
An example of two linear simultaneous equations is:
7x + 8t = 22
3x + 5t = 11