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Nice problem, but at the end it would probably been easier to just use the result(A+1/2)^2=E( (A+1/2)^2 ) = 11 + 1 +1/4 =49/4=7^2/2^2, so A€{3,-4} and then1=3*k/m - 4*(m-k)/m = 7*k/m - 4, so k/m=5/7.
You're right. That's a pretty natural finish 👍
Nice problem, but at the end it would probably been easier to just use the result
(A+1/2)^2=E( (A+1/2)^2 ) = 11 + 1 +1/4 =49/4=7^2/2^2, so A€{3,-4} and then
1=3*k/m - 4*(m-k)/m = 7*k/m - 4, so k/m=5/7.
You're right. That's a pretty natural finish 👍