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QUESTION

If ${\bf a}=2{\bf i}-3{\bf j}+{\bf k}$ and ${\bf b}={\bf i}-{\bf
j}$  evaluate ${\bf a}\cdot{\bf b}.$

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ANSWER

$\mathbf{a\cdot
b}=(2,-3,1)\cdot(1,-1,0)=2(1)+(-3)(-1)+1(0)=2+3+0=5$





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