Find all negative terms of the arithmetic sequence for which the nth term = 20n−78.

-58, -38, -18

Step-by-step explanation:

if for the nth term, the value is 20n-78, then for the 1st term, the value will be 20(1)-78

So we just need to use this formula for every term, starting from the 1st, until the value is no longer negative

20(1)-78 = 20-78= -58

20(2)-78 = 40-78= -38

20(3)-78 = 60-78= -18

20(4)-78 = 80-78= 2

so those are the only negative terms

cya at RSM today