SOLUTION: Hi! Im having difficulty understanding why my answer is wrong in the following problem: In triangle ABC, centroid D is on the median "AM". "AD"= x+6 and "DM"= 2x-5. Find "AM"

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Question 257344: Hi! Im having difficulty understanding why my answer is wrong in the following problem:
In triangle ABC, centroid D is on the median "AM". "AD"= x+6 and "DM"= 2x-5. Find "AM"
anything with the quotations means that it is a line.
so i solved it by these steps:
1) 2x-5 = x+6.....x=11
2) 11+6=17, 22-5=17 ( i did this because i substituted x into the equations given for the length of "AD" and "DM"
3) "AM"= 34
Please help me! Thanks!
Answer by drk(1908) (Show Source):
You can put this solution on YOUR website!
The centroid cuts the median into the proportions 2/3 and 1/3, but the ratio of the lengths is 2:1.
From your information, we have
x+6 = 2(2x-5)
solving for x, we get
x+6 = 4x - 10
16 = 3x
16/3 = x.
--
16/3 + 6 = 34/3 = AD
2*(16/3) - 5 = 17/3 = DM
Ad + DM = 34/3 + 17/3 = 51/3 = 17.