Medium
Find the sum of the first 14 terms of the AP with first term -3 and common difference -2.
Explanation
Explanation
The sum of the first n terms of an AP is Sₙ = n/2 × [2a + (n-1)d]. Here n = 14, a = -3, d = -2. So S = 14/2 × [2(-3) + (14-1)(-2)] = 14/2 × [-6 + -26] = 14/2 × -32 = -224.
PRO TIP
Re-check your working by substituting the answer back into the original question.