Find the sum of first 20 terms of the A.P. 7, 11, 15, 19,
Answers
Answered by
3
Answer:
n=20, a=7,d=a2-a1=11-7=4
d=4
an=a+(n-1)×d
an=7+(20-1)×4
an=7+19×4
an=83
Answered by
6
Answer:
a=7
d=
Step-by-step explanation:
11-7=4
sum of 20th term=n/2(2a+(n-1)d)
=20/2(2*7+(20-1)4)
=10(14+76)
=10*90
=900
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