

Course 1, Unit 7  Quadratic Functions
Overview
In conventional high school algebra curricula, the most prominent nonlinear
expressions and functions are quadratic polynomials. In CorePlus
Mathematics Course 1, earlier and greater attention is given
to Exponential Functions due to their relevance and to capitalize on
the connections with linear functions. This unit begins the study of
Quadratic Functions that will be continued in CorePlus Mathematics Courses 24.
Thus, this unit should be treated as an introduction to Quadratic Functions.
Some of these topics are often introduced in middle school math courses.
Encourage your student to recall these ideas. Some of these questions may
be helpful.
To be proficient in the use of quadratic functions for problem solving,
students must have a clear and connected understanding of the numeric,
graphic, verbal, and symbolic representations of quadratic functions
and the ways that those representations can be applied to patterns in
real data. The lessons of this unit are planned to develop each student's
intuitive understanding of quadratic patterns of change and technical
skills for reasoning with the various representations of those patterns.
Understanding and skill in working with quadratic functions is developed
in three lessons.
Key Ideas from Course 1, Unit 7

Quadratic function rule: a function with equation in the
form y = ax^{2} + bx + c. The
relationship between height (in feet) of a kicked ball and its time
in flight (in seconds) is modeled reasonably well by a quadratic
function. For example, if h = 16t^{2} + 50t + 3,
the ball's height in feet after t seconds depends on
the initial height (3 feet in this example), the initial velocity
of the ball (50 ft/sec in this example), and the effect of gravity
(indicated by the 16 ft/sec in this example).

Quadratic function graph:

Quadratic function table:

Expanding and factoring quadratic expressions: Applications
of the distributive property are used to multiply two binomial expressions
and to factor binomials and trinomials. (See pages 491498.
See Strategies 1 and 2 on page 497.)

Identify the maximum or minimum points and xintercepts: Students
use factoring techniques, symmetry, and/or the quadratic formula
to find key points on a quadratic graph. (See pages 492498.)

Solve quadratic equations: Quadratic equations of the form ax^{2} + c = d, ax^{2} + bx = 0,
and ax^{2} + bx + c = d are
solved symbolically and by using the quadratic formula. This topic
is practiced in various Review tasks and further developed in subsequent
units. (See pages 510517.)
