If y varies directly with x, and if y = 2/3 when x = 1/4, how do you find the direct variation equation?

1 Answer
Apr 6, 2016

#3y=8x#

Explanation:

If #y# varies directly with #x# then
#color(white)("XXX")y=c*x# for some constant of variation #c#

If #(x,y)=(1/4,2/3)# is a solution to this equation, then
#color(white)("XXX")2/3 = c*1/4#

#color(white)("XXX")rarr c=2/3 *4/1 = 8/3#

So
#color(white)("XXX")y=8/3x#
or (clearing the fraction)
#color(white)("XXX")3y=8x#