Slope Intercept Form

Writing an equation when given 2 points

1. Calculate slope 2. Plug slope and one point given into the formula: y=mx+b 3. Solve for b 4. Rewrite with only the slope and the y intercept

How to graph y=mx+b

1. Make sure equation is in slope-intercept form 2. Identify the slope and the y-intercept 3. Plot the y intercept (always BEGIN with b!) 4. Apply the slope using y-intercept as your first point

negative slope plotting

down and right, up and left

How to find slope from a table...

find the change in y and the change in x. Put y over x to get rise over run.

y=kx facts

k cannot be 0, k stands for constant variation, graph will always be a straight line and go through the origin

To get k you do...

k= y/x

Finding slope

rise/run or second y minus first y over second x over first x

Horizontal line means...

slope of zero (0 in the numerator)

If x's are all the same the slope is...

undefined

positive slope plotting

up and right, down and left

Undefined slope

vertical line (0 in the denominator), write equation as "x equals)

Slope intercept form

y = mx+b

Direct variation

y=kx (2 quantities increase or decrease at the same tare)

What does b represent?

The y intercept (where the line crosses on the y-axis)

How do u know if a problem has direct variation?

If it fits the format, y=kx

How do u know if a table is direct variation?

If their constant variation is the same at each level. Ex. y output 8 over x input 4 will give you 2, then y output 14 over x input 7 will also give you 2, so it's direct variation.

What does m represent?

Slope