22.
The sum of first 12 terms of the series -7 + 4 +15 + 26 is
A. 640
B. 426
C. 642
D. 426
Answers
Answered by
1
Answer:
The sum of n terms of an AP is n/2*(2a+(n-1)d) where n is no. of terms d is common difference and a is the first term
Step-by-step explanation:
using above we have th AP as
a=-7
d=11
n=12
So putting the value in above equation we have sum = 642 optiion C
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