Nicki shows a magic trick to three of her friends. Each of those friends shows it to three more friends. If the pattern is repeated two more times, how many people now know the trick?

121

Step-by-step explanation:

1st step she tells 3 people

2nd step 3x3=9

3rd step 9x3=27

4th step 27x3=81

1(nicki)+3+9+27+81= all the people who know about the trick

=121

The matrix that best represents the linear system of equations must be written vector by vector in each of the rows. That is, components x in column 1, components and in column 2 and component z in column 3. In column 4 you write the results. Attached solution.