Answer:
In given series of AP first term a=7, common difference d= 10
2
1
−7=
21
7
and last term l=84
Since, l=a+(n−1)d
⇒84=7+(n−1)
⇒84−7=(n−1)
⇒77=(n−1)
⇒77×
=n−1
⇒22=n−1
⇒n=23
Since, S
n
=
(a+l)
⇒S
23
(7+84)
=91×
2093
=1046
Step-by-step explanation:
I hope it is helpful
ya aatmagyan..
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Verified answer
Answer:
In given series of AP first term a=7, common difference d= 10
2
1
−7=
2
21
−7=
2
7
and last term l=84
Since, l=a+(n−1)d
⇒84=7+(n−1)
2
7
⇒84−7=(n−1)
2
7
⇒77=(n−1)
2
7
⇒77×
7
2
=n−1
⇒22=n−1
⇒n=23
Since, S
n
=
2
n
(a+l)
⇒S
n
=
2
23
(7+84)
⇒S
n
=91×
2
23
⇒S
n
=
2
2093
⇒S
n
=1046
2
1
Step-by-step explanation:
I hope it is helpful
Answer:
Answer:
In given series of AP first term a=7, common difference d= 10
2
1
−7=
2
21
−7=
2
7
and last term l=84
Since, l=a+(n−1)d
⇒84=7+(n−1)
2
7
⇒84−7=(n−1)
2
7
⇒77=(n−1)
2
7
⇒77×
7
2
=n−1
⇒22=n−1
⇒n=23
Since, S
n
=
2
n
(a+l)
⇒S
n
=
2
23
(7+84)
⇒S
n
=91×
2
23
⇒S
n
=
2
2093
⇒S
n
=1046
2
1
Step-by-step explanation:
I hope it is helpful
ya aatmagyan..