SOLUTION: If one root of the equation x^2 - mx + 2=0 is double the other, find the value of m.

SOLUTION: If one root of the equation x^2 - mx + 2=0 is double the other, find the value of m.

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Question 1129801: If one root of the equation x^2 - mx + 2=0 is double the other, find the value of m.
Answer by math_helper(2461) (Show Source): You can put this solution on YOUR website!
let the roots be r and t, with r = 2t

Then we can say:
(1)
(2)

Substituting r=2t into (1):

This last equation and (2) can be solved for t in terms of m:
t = 3/m ( �> r = 6/m )

Plugging in t = 3/m into (2):

m = +/- 3

Both values of m work as solutions:
m=-3:
�> �> x = -1 and x = -2

m=3:
�> �> x = 1 and x = 2

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