Find the equation of the line that contains the given points. (Let y be the dependent variable and let x be the independent variable.)p1(4,5) p2(3,-4) could someone help me please?

Question

anonymous · Answer

Do you recall the formula for the slope of a line?

anonymous · Answer

given two points?

amistre64 · Answer

find the slope by subtracting one set of points from the other olike this:

  (4, 5)
-(3,-4)

  (4, 5)
 (-3,4)
-------
  (1,9)  slope = y/x = 9/1 = 9

anonymous · Answer

y-y1=m(x-x1)

amistre64 · Answer

( x , y  )
-(x1,y1)
--------
  yes....

anonymous · Answer

ok thanks!

amistre64 · Answer

i find it easier to stack them; and subtract the bottom from the top....

then slope = m = y/x

anonymous · Answer

you know I haven't thought of that . It looked too easy!

amistre64 · Answer

so we have an equation now that looks like:

y = 9x + b   ; plug in one of the points to solve for b

amistre64 · Answer

5 = 9(4) + b

5 = 36 + b

5 -36 = b

-31 = b
....................

y = 9x -31

amistre64 · Answer

another format is to put all the variables to one sidelike this:

-9x +y = -31   ; but some textbooks hate to have a (-) out front so they do this:

9x -y = 31

anonymous · Answer

ok the first way looks easier!

amistre64 · Answer

:)

y = 9x-31 is the "slope,intercept" form.

9x-y=31 is the "standard" form