1. Linear Equations in Two Variables
Ms. Zuniga
IB Math Studies 1
Room 9222

2. I. Slope-Intercept Form
y = mx + c
m: slope/gradient = rise/run = Δy/Δx
c: y-intercept

3. Gradient Positive Negative Zero (horizontal) undefined (vertical) y=#
x=#

4. Point-gradient Form
y – y1 = m(x – x1)

5. Standard Form: Ax + By + C = 0
There can be no fractions or decimals (A, B, and C are integers)
A must be greater than 0
Must be set = 0
The GCF of A, B, and C = 1

6. Graphing You should be able to graph:
Given 2 points (plot the points and connect with a line)
Given 1 point and gradient (first plot point and from that point follow the gradient)
In slope-gradient form (put a pt. on the y-axis where the y-int is located, then from that pt. follow the gradient)

7. Writing Equations You should be able to write an equation:
Given the y-intercept and gradient (just plug the values into the equation y = mx + c)
Given the gradient and 1 point (substitute values of y, m and x to solve for c which is the y-intercept. Then rewrite the equation as y=mx + c)
Given 2 points (find gradient first, choose 1 pt. to substitute values of y, m, and x as discussed above)

8. Parallel and Perpendicular Lines
Parallel lines have the same gradient
Perpendicular lines have negative reciprocal gradients