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## Homework Statement

A=(x,3,1) ,B=(x,-x,2)

Determine the value of x if the vector perpendicular to A and B is given by C=(10,-4,-4)

## Homework Equations

## The Attempt at a Solution

Find A cross B , let A cross B be D . Then D cross C = zero (since they are perpendicular to both A and B) . This sounds logic but there will not be an answer for x. What is wrong?

Then I tried to use dot product A dot C=0, and B dot C=0. Yet the answer of two x are different.

Please guide. Thanks