MYP Standard Mathematics Sequences, Formulae and Proportional Reasoning Key Definitions

A relationship where $y$ is proportional to a positive power of $x$: $y\propto x^n$ with $n>0$, so $y=kx^n$.

A relationship of the form $y=kx$, where $k$ is a constant. If $x$ is multiplied by a factor, $y$ is multiplied by the same factor.

Its subscript (for example, the index of $u_5$ is 5), which indicates the term’s position in the sequence.

A relationship of the form $y=\frac{k}{x}$, where $k$ is a constant. If $x$ is multiplied by a factor, $y$ is divided by the same factor.

A linear proportional relationship with a negative constant of variation: $y=-kx$ where $k>0$.

A non-zero constant, usually called $k$, that links two proportional variables (also called the constant of variation).

A rule that defines terms using earlier term(s), often together with a starting term (such as $u_1$).

An ordered list of numbers where each number in the list is called a term.