Which system of equations has exactly one solution?
0
2x-4y= 8
x+y=7
o
3x+y=-1
6x+2y=-2
3x+3y=3
-6x-6y=3
3x-2y=4
-3x+2y=4

all work is pictured and shown

34

step-by-step explanation:

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4