Simple dot product [inner product] (verification)

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seto6
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Homework Statement


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Homework Equations



know dot product

The Attempt at a Solution


PART A
Handwritten work verifying a dot product: u·v = w·v, with w = [1, 2, 3], v = [2, 4, 6], u = [x, 2, 4], leading to 2x + 8 + 24 = 2 + 8 + 18 and x = -2, with typed notes on the right.


PART B
not sure what's it asking for

help would be great
 
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Well, what you posted is the answer to the B part actually :wink: Notice the "for all v" part in A. Specific example of u,v does the trick for B, not for A. Hint for A: (u-w)*v = 0 for all v. What does it say about u - w?