Pre Calculus

Question

Find the dot product between the vectors u and v: u = 6i – j and v = 4i +2j .

a)11

b)22

c)-11

d)-22

Answer 1

To get the dot product of the two vectors

multiply the "i" coefficients and add that to

multiplying the "j" coefficients:

 

6 * 4  +  (-1) * 2  =  24 + -2  = 22

 

Be careful of the "-" sign: it gets stuck to the number that

follows it, so the first vector has "-1" for its j component.