In three dimensions, the cross product of two vectors is defined as shown below

Then, solving the determinant

In our case,

Where we used the formula for AxB to calculate ixj.
Finally,

Thus, (i+j)x(ixj)=i-j
If she is starting on day 1 with 0 followers and advances up 2 followers every day, by day "n" she would have 28 followers.
Answer:
17
Step-by-step explanation: