Linear Equations in Two Variables

1
Linear Equations in Two Variables

• Ms. Zuniga
• IB Math Studies 1
• Room F239

2
I. Slope-Intercept Form

• y mx c
• m slope/gradient rise/run ?y/?x
• c y-intercept

3
Gradient

• Positive

• Negative

• Zero (horizontal)
• y

• undefined (vertical)
• 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 ymx
  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