Question Detail
Question
Find the sum of the first 77 terms of the arithmetic progression 4, −3, −10, ...
Correct Answer
Option A is the correct answer.
Detailed Explanation
a=4, d=−7, n=77. S_n = 77/2[8 + 76×(-7)] = 77/2[8 - 532] = 77/2×(−524) = 77×(−262) = −20174.
Hint
Common difference is −7.