Answer:
510
Step-by-step explanation:
Formula:
Sn = n/2 [ 2a1 + (n - 1) d ]
S12 = 12/2 [ 2(4) + (12 - 1) 7 ]
S12 = 12/2 [ 8 + (11) 7]
S12 = 12/2 (8 + 77)
S12 = 12/2 (85)
S12 = 6 (85)
S12 = 510
Answer:
Find the sum/Plus of the first 12 terms of the arithemetic sequence 4,11,18,...
Step-by-step explanation:
