Question

if d=5 n=10 an=68 then find first term​

Answer 1

Answer:

a=8,a

n

=62,s

n

=210

a

n

=a+(n−1)d

62=8+(n−1)d

54=(n−1)d

s

n

=

2

n

[2a+(n−1)d]

210=

2

n

[16+(n−1)d]

420=n[16+54]

420=70n

n=6

54=(6−1)d

d=

5

54

Answer 2

Answer:

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Class 11

>>Applied Mathematics

>>Sequences and series

>>Arithmetic progression

>>In an AP, given a = 8 , an = 62 ,Sn = 21

Question

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In an AP, given a=8,a

n

=62,S

n

=210m find n and d.

Easy

Solution

verified

Verified by Toppr

a=8,a

n

=62,s

n

=210

a

n

=a+(n−1)d

62=8+(n−1)d

54=(n−1)d

s

n

=

2

n

[2a+(n−1)d]

210=

2

n

[16+(n−1)d]

420=n[16+54]

420=70n

n=6

54=(6−1)d

d=

5

54