How many terms of A.P.3,8,13,18… will make the sum 819
Answers
Answered by
2
Answer:
Sn=n/2(2a+n-1*d)
819=n/2(6+(n-1)5)
1638=n(1+5n)
1638=n+5n^2
5n^2+n-1638=0
-1 plus minus 181/10
n=18 or -92
n not equal to -92 because n is positive
Step-by-step explanation:
Answered by
1
Answer:
a=3 d=8-3=5 Sn=819
Sn=n/2[2a+(n-1)d
819=n/2[2*3+(n-1)5
1638=n[1+5n]
5n square+n-1638=0
5n square+91n-90n-1638=0
n(5n+91)-18(5n+91)
n=18 answer
Step-by-step explanation:
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