posted by Anonymous .
I have an assignment that asks me to write an equation in slope-intercept, point-slope, or standard form for the information given and to explain why the chosen form would be best. Below is the information given.
1. passing through (-1,4) and (-5,2)
2. that has slope 2 and y intercept 4
3. that has an x-intercept of 6 and a y-intercept of 3
4. that passes through (1,2) and has a slope of -5/3
I chose point-slope for the first one, slope-intercept for the second, slope-intercept for the third, and point-slope for the fourth. Do you think my answers are good, or would you choose different forms for some of them?
actually, any method should work for any of those conditions,
in #3, I would use the intercept-intercept form
if the x-intecept is 'a' and the y-intercept is 'b', then the equation can be written simply as
x/a + y/b = 1
so x/6 + y/3 = 1
x + 2y = 6 , all done!
If I know the slope and a point, I use a method that given me the equation in about 3 lines
- based on the fact that for
Ax + By = C, the slope is -A/B
if you give me the slope I can reverse that and start with the completed left side of the equation,
given slope as -5/3 and the point (1,2) , your #4
the equation has to be
5x + 3y = C , but (1,2) lies on it, so
5(1) + 3(2) = C
C = 11
equation: 5x + 3y = 11
advantage, no fractions!