Glossary
Concavity
Describes the direction in which the graph of a function opens; it can be concave up (like a cup) or concave down (like a frown).
Example:
A graph showing accelerating growth would exhibit upward concavity, while a graph showing decelerating growth would show downward concavity.
Constant function
A polynomial function where the highest power of the variable is zero, resulting in a horizontal line graph.
Example:
If the temperature in a perfectly insulated room is a constant function , it means the temperature remains 22 degrees Celsius over time.
Critical points
Points in the domain of a function where the derivative is zero or undefined, often corresponding to local maxima or minima.
Example:
To find the exact time a ball reaches its maximum height, you would calculate the critical points of its height function.
Degree (of a polynomial)
The highest power of the variable in a polynomial function.
Example:
For the polynomial , the degree is 5.
Even degree (polynomials)
Polynomial functions where the highest power of the variable is an even number, causing their end behavior to go in the same direction.
Example:
A quadratic function like is an even degree polynomial, and both ends of its graph point upwards.
Global maximum
The absolute highest point of the entire graph of a function over its entire domain.
Example:
The highest point on Mount Everest is the global maximum elevation on Earth.
Global minimum
The absolute lowest point of the entire graph of a function over its entire domain.
Example:
The deepest point in the Mariana Trench represents the global minimum elevation on Earth.
Increasing/Decreasing intervals
Intervals on the x-axis where the function's y-values are consistently rising (increasing) or falling (decreasing) as x increases.
Example:
If a company's stock price graph shows an increasing interval from 9 AM to 1 PM, it means the stock value was rising during those hours.
Inflection points
Points on the graph of a function where the concavity changes, transitioning from concave up to concave down or vice versa.
Example:
On a graph showing the spread of a rumor, an inflection point might indicate when the rate of new people hearing the rumor starts to slow down.
Leading coefficient
The coefficient of the term with the highest power of the variable in a polynomial function.
Example:
In the polynomial , the leading coefficient is -0.5, which tells us the graph opens downwards.
Local maximum
A point on the graph of a function where the function's value is greater than or equal to the values at all nearby points within a specific interval.
Example:
On a graph representing a day's temperature, the peak temperature reached in the afternoon is a local maximum.
Local minimum
A point on the graph of a function where the function's value is less than or equal to the values at all nearby points within a specific interval.
Example:
The lowest point a roller coaster reaches in a dip before climbing again is a local minimum.
Polynomial function
A function expressed as a sum of terms, where each term is a constant multiplied by a variable raised to a non-negative integer power.
Example:
The trajectory of a rocket launch can be modeled by a polynomial function like , where is time and is height.
Zeros (of a polynomial function)
The x-values where a polynomial function crosses the x-axis, meaning the function's output is zero ($f(x) = 0$).
Example:
If a company's profit is modeled by , the zeros of would indicate the break-even points where profit is zero.