What is the dot product of $< 2, 0, 7 >$ $<2,0,7>$ and $< - 4, 9, - 1 >$ $<-4,9,-1 >$ ?

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Answer 1 · 2015-12-22T15:16:35

-15

The usual dot product for the vectors $x=(x_1,x_2,...,x_n)$ and $y =(y_1,y_2,...,y_n)$ in $RR^n$ is $x.y = sum_(i=1)^nx_iy_i$ .

We apply it here : $(2,0,7).(-4,9,-1) = 2*(-4) + 0*9 + 7*(-1) = -15$

What is the dot product of <2,0,7><2,0,7><2,0,7> and <-4,9,-1 ><−4,9,−1><-4,9,-1 >?