Find D[ξ-2η] when ξ and η are independent

by MCTG   Last Updated May 15, 2019 18:20 PM

My question is:

Random variables ξ and η are independent and with with equal probabilities acquires values -3, 0, -3. Find D[ξ-2η]

I've tried to solve like this:

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But I'm not sure if this is the right answer.

Any help appreciated, Thanks!

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