Question

please give the steps by step solution for Q.18

Answer 1

A.B = ABcosteta 3x1+2x-1+3x2=3-2+6=7

Answer 2

(ax)+(by)+(cz)

when the two given vectors are ai+bj+ck and xi+yj+zk; i,j,k being three unit vectors perpendicular to each other(representative of the coordinate axes)

Now comparing your question with the above stuff,

2i+2j+3k is equivalent to ai+bj+ck

and

3i+6k+nk=3i+0j+(6+n)k

the dot product is sum of the product of the coefficients,that is

2*3+3*(6+n)

Now equating this to zero and dividing both sides by 3, we get

2+6+n=0 which gives n=-8