Section 2.3: Quick Graphs of Linear Equations

Mr. Dreyer

Algebra 2 Lv 1

1Warmup

  2. Welcome/expectations signatures on desk
  3. Got calculators?
  4. Write down homework: Read Section 2.3, p. 82-85. Problems: 1-3, 5-15 odd numbered, 16-18, 19-35 odd, 37-39, 41-79 odd.

  5. What is the slope of the graph of this equation:

    3⁢y-6x=9

2Slope-intercept form

We can learn about the graphs of linear equations by forcing the equations into certain forms.

Equation Points Slope y-int
y=2⁢x+3 (0,)(1,)
y=-1⁢x+2 (0,)(1,)
y=12⁢x-4 (0,)(1,)

The slope-intercept form of a linear equation is

y=m⁢x+b

What is its slope? Its y-intercept?

(examples)

3The “standard form”

It's a misleading name; it's no more standard than the slope-intercept form, but that's its name so we deal with it!

The standard form of a linear equation is in the form

A⁢x+B⁢y=C

How do we find the y-intercept?

A0+B*y = C B⁢y = C y = CB

How do we find the x-intercept?

So we see that the standard form tells us both intercepts.

How do we convert this form to the slope-intercept form?

How do we convert the slope-intercept form to this form?