Unit 5: Quadratic - Garde 9 Flashcards
Distributive Law
a(b + c) = ab + ac
One term
monomial
Two terms
binomial
Three terms
trinomial
Expanding monomials
- properties of exponents
a^m x a^n = a^(m+n)
Multiplying two binomials
(a + b)(c + d) = ac + ad + bc + bd
FOIL
Square of a binomial
(a + b)^2 = (a + b)(a +b) = a x a + a x b + b x a + b x b
a^2 + 2b + b^2
Product of conjuagates
(a + b)(a - b) = a^2 - b^2
Factoring
1) GCF: greatest common facotr
- it may be constant variable or both.
2x^2 - 8x = 2x(x - 4)
2) DOS: Check for a difference of square
- first a perfect square
- second a perfect square
- minus between two terms
- if so: factor as (root of first + root of second) (root 1 - root 2)
4x^2 - 361 = 2x - 19
*if not, you can not factor it
Factorizing expressions with four terms
Grouping them in two pairs
- ax^2 + ax + 2x + 2
= ax(x + 1) + 2 (x + 1) {factorising each pair}
= (x + 1)(ax + 2) {(x + 1) is a common factor}
Quadratic trinomial facorization
ax^2 + bx + c
- x is a variable
- a, b, c are common constants, a is not equal to 0
(x + 1)(x +6)
x^2 + x + 6x + 6
x^2 + 7x + 6
x^2 + (p + q)x + pq
- the coefficient of x is the sum of p and q
- the constant term is the product of p and q
(x + p)(x +q)
Function Notation
linear function:
y = mx + b (x-y notation)
f(x) = mx + b (function notation)
f(x) is “f of x”
Quadratic function
f(x) = ax^2 + bx + c
Parabolas
-a: concave down
a: concave up
a is the “leading” coefficient
c: y-intercept
b: coefficiant
axis of symmetry: x = x-intercept of vertex
f(x), x are variables
Vertex
minimum or maximum value on a parabola
Quadratic term
ax^2
Linear term
bx
Constant term
c
Method 2 of factoring quadratic trinomials
6x^2 - 7x -10
- multiply a and c
6x^2 x 10 = -60x^2
- find two factors of -60 that up to -7
-12x and 5x
- Replace bx (7x) with these factors
6x^2 - 12x + 5x -10
- then simplify
6x(x - 2) + 5(x - 2)
(6x + 5)(x - 2)
x-intercept of a function, f(x)
are also called the “zeros”
Factored form
y = a(x - p)(x - q), a does not equal zero
- axis of symmetry: (p + q)/2
- p and q are x-intercepts
Standard form
y = ax^2 + bx + c
axis of symmetry: -b/2a
vertex: -b/2a, f(-b/2a)
Vertex form
y = a(x - h)^2 + k, a does not equal zero
- (h, k) are the vertex
Factored to Standard form
look in book
Standard to vertex form
(b/2)^2 to find the number needed to add and subtract from both sides
- factor from there and find k
Function
A set of ordered pairs in which each first coordinate corresponds to a distinct second coordinate (no vertical points in a function)
Vertical line test (VLT)
used to determine if the given graph represents a function
Ex: if a vertical line intersects the line more than once, it does not represent a function.
Domain
the area x can occupy from a line, parabola or circle
Range
the area y can occupy from a line, parabola or circle
Zero product theory (null factor law)
- if a x b = 0, then a = 0 or b = 0
ax^2 + bx + c
Solutions are x-intercepts of the graph.
To factor: - terms of LHS (leave zero on RHS)
- Simplify: combine terms
- Factor LHS
- Apply zero product theorem