Glossary — Algebra

Asymptote — a line that a graph gets closer to but does not meet.

Binomial — an algebraic expression with two terms, such as $x+3$.

Coefficient — the number multiplying a variable, such as $5$ in $5x$.

Common difference — the amount added to each term to get the next term in an arithmetic sequence.

Discriminant — the value $b^2-4ac$ in a quadratic equation $ax^2+bx+c=0$; it tells you how many real roots the equation has.

Equation — a statement that two expressions have the same value, shown by an equals sign.

Expression — numbers, variables and operations written together without an equals sign.

Factorise — rewrite an expression as a product of factors.

Function — a rule that gives one output for each permitted input.

Gradient — the change in the vertical coordinate divided by the change in the horizontal coordinate along a line.

Identity — an equation that is true for every permitted value of its variable.

Inequality — a comparison that uses a symbol such as $<$, $>$, $\leq$ or $\geq$.

Intercept — the point where a graph crosses an axis.

Iteration — repeatedly applying a rule, using each answer as the next input.

Like terms — terms with the same variable part, such as $3x$ and $-2x$.

Linear sequence — a sequence with the same difference between each pair of consecutive terms.

Linear relationship — a relationship that can be represented by a straight-line graph.

Position-to-term rule — a rule that gives a term from its position in a sequence.

Quadratic equation — an equation whose highest power of the variable is $2$.

Quadratic sequence — a sequence with constant second differences.

Root — a value of a variable that makes an equation true; on a graph, a root is where the curve crosses or touches the horizontal axis.

Substitute — replace a variable with a given value or expression.

Term — one part of an expression or one number in a sequence.

Term-to-term rule — a rule that tells you how to get each sequence term from the one before it.

Variable — a letter that stands for a number that can change or is not yet known.

Turning point — a point where a graph changes from increasing to decreasing, or from decreasing to increasing.

Zero-product rule — if two factors multiply to give zero, at least one factor must be zero.