SAT alg n adv Flashcards
What is linear equation slope-intercept form, and what do the letters represent?
y=mx+b where m is the slope, and b is the y-intercept
What is linear equation standard form, and how do you graph it?
Ax+By=C
To graph, you must convert it to slope-intercept form
What is linear equation point slope form?
y-y1=m(x-x1) Where y is the x1 and y1 are the coordinates of a point, and m is the slope
What are the rules for linear equation standard form?
- A must be positive
- All terms must be integers
Methods for solving systems of equations
- Substitution (substitute 1 variable for another)
- Elimination (eliminate a variable)
What must you do when solving an inequality and you divide/multiply by a negative?
You flip the inequality sign.
What is quadratic function:
Standard form
Intercept form
Vertex form
Standard form: Y= Ax^2+By+C
Intercept form: y=a(x-p)(x-q) where P and Q are the coordinates of the X intercepts
Vertex form: y=a(x-h)^2 +k where the vertex is at (h,k) (to graph, plug x-intercept coordinates into equation to find the y-coordinate of the vertex)
What are the steps to graphing a quadratic equation?
- Find the Axis of Symmetry with the equation (-b/2a)
- If a is positive, the graph opens towards the positive
If a is negative, the graph opens towards the negative - Plug the Axis of Symmetry into the equation to find the vertex
- Find the Y-intercept
- Find the X-intercept either by factoring, completing the square, or the quadratic formula
Tip: If A is bigger, the graph is narrower
If necessary, use a table to determine points on the graph
What do you need to know to graph a quadratic equation?
Axis of symmetry (-b/2a), vertex, x intercepts, y intercept
What is the goal of factoring?
To find the X-intercepts of a quadratic function
How do you factor when A=1?
x^2+5x+6
A= 1 B= 5 C=6
- Find what adds to adds to B and multiplies to C.
It would be 2 and 3
The factored equation now becomes
(x+2)(x+3)
How do you factor when A isn’t 1?
You
What is the quadratic formula?
In words:
X intercepts = -b plus or minus the square root of b squared minus 4 ac all over 2a
You use factor by grouping.
3x^2 -4x -15
- Find what multiplies to (A*C) but multiplies to B.
-9 & 5 - Split B into those numbers and group the 2 sides.
3x^2 -9x +5x -15
(3x^2-9x) (5x-15) - Factor the 2 sides
3x(x-3) 5(x-3) - Group like terms
(3x+5)(x-3)
Exponential growth and decay
yp=a(b)^x
If b>1, it’s growth
If B<1, it’s decay