Answer:
{1, 3, 5, 7}
Step-by-step explanation:
There are four possibilities:
AD = AB -BC -CD = 1 -2 -4 = -5
AD = AB +BC -CD = 1 +2 -4 = -1
AD = AB -BC +CD = 1 -2 +4 = 3
AD = AB +BC +CD = 1 +2 +4 = 7
Possible lengths of AD are 1, 3, 5, 7.
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The negative sign means the segment is added toward the left instead of toward the right. A final negative value means D is left of A, instead of to the right.
