first term and common difference of an A.P are 6 and 3 respectively ;find S27
Answers
Answered by
19
Answer in 2 methods:
1st method:
since ,a=6 , d=3
we need to find S27=?
HERE, Sn=n/2{2a+{n-1}d}
=27/2{2×6+{27-1}3}
=27/2{12+26×3}
=27/2{90}
=27×45
=1215
hence sum to 27 terms is 1215
2nd method:
Given
a=6
n=27
d=3
S27=?
n=27
SOLUTION
S27=(n/2){2a+(n-1)d}
=(27/2){2(6)+(27-1)(3)}
=(27/2){12+26×3}
=(27/2)(12+78)
=(27/2)(90)
=13.5×90
=1215
ANSWER: Sn=1215
Step-by-step explanation:
Answered by
4
Answer:1188
Step-by-step explanation: a=6, d=3,n=27
sn=n/2[2a+(n-1)d]
s27=27/2[2(6)+(27-1)3]
=13.2[12+ 78]
=13.2[90]
=1188
therefore, the answer is 1188
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