If y varies directly with x and y = -4 when x = 12.5, how do you find y when x = 24?

1 Answer
Rafael
Sep 29, 2015

#y=-7.68#

Explanation:

A direct variation can be written as #y=kx#. Since we are given a matched #x# and #y# value, we can first compute for the constant of variation #k#.

#y=kx#
#(-4)=k(12.5)#
#(1/12.5)(-4)=(1/cancel12.5)k(cancel12.5)#
#-4/12.5=k#
#color(blue)(k=-0.32)#

Now that we know the constant of variation, we can now solve for the value of #y# when #x=24#.

#y=color(blue)(k)x#
#y=color(blue)((-0.32))x#
#y=color(blue)((-0.32))(24)#
#color(red)(y=-7.68)#

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