How do you find the slope and y-intercept given #9x-3y= -1#?

1 Answer
Alan P.
Jul 14, 2015

Slope #=3#
y intercept is #1/3#

Explanation:

Slope
From standard form:
#color(white)("XXXX")##Ax+By = C#
the slope can be determined as #(-B/A)#
or
you could convert the given equation into slope intercept form:
#color(white)("XXXX")##9x-3y =-1#

#color(white)("XXXX")##rarr -3y = -9x-1#

#color(white)("XXXX")##= y = 3x+1/3#
#color(white)("XXXX")##color(white)("XXXX")#(slope intercept form)

y-intercept
If you used the "convert to slope-intercept form" version (above) then the y-intercept can be read directly from the equation (as #1/3#).

If you used the slope #= (-B/A)# version
set #x=0# in the given equation and solve for #y#
#color(white)("XXXX")##9(0) - 3y = -1#

#color(white)("XXXX")##rarr -3y = -1#

#color(white)("XXXX")##rarr y = 1/3#

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