Assume that , , and . What is the value of ? Please help!
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Originally Posted by Del Assume that , , and . What is the value of ? Please help! From $\displaystyle |\vec u| = 3$ you know that $\displaystyle \vec u \cdot \vec u = 9$ Now expand the given term: $\displaystyle 7 \vec u \left(4 \vec u - 3 \vec v \right) = 28 \vec u \cdot \vec u - 21 \vec u \cdot \vec v = 28 \cdot 9 - 21 \cdot 3 = 189$
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