W is the midpoint of DY. If #DW=x^2 +4x# and #WY=4x+16#, how do you find DY?

1 Answer
Alan P.
Oct 27, 2016

Provided the lengths are non-zero
#color(white)("XXX")color(green)(abs(DY)=64)#

Explanation:

If #W# is the midpoint of #DY# then
#color(white)("XXX")abs(DW)=abs(WY)#

#color(white)("XXX")x^2+4x=4x+16#

#color(white)("XXX")x^2=16#

#color(white)("XXX")x=+-4#

If #x=-4#
#color(white)("XXX")x^2+4x=0 and 4x+16=0#
so the total length #abs(DY)=abs(DW)+abs(WY)=0#

If #x=+4#
#color(white)("XXX")x^2+4x=32 and 4x+16=32#
so the total length #abs(DY)=abs(DW)+abs(WY)=32+32=64#

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