vivianrush Group Title Algebra 2 help please one year ago one year ago

$\sum_{k=1}^{18}7x-4$ 18 is the stopping point because it is the number of rows. You start from 1 row to 18 rows. When you start with k=1, you can substitute for x in 7x-4---> 7(1)-4=3 so that's right in the sequence 3+....