Question

30. Sum of the first n terms of on A.P is 5m² -3n. Find the A.P and also find its 16h term.​

Answer 1

Answer:

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Answer 2

Answer:

AP=2,12,22

16th term(a16) =152

Step-by-step explanation:

Sn=5n^2-3n

Let n=1

S1=5(1)^2-3×1

=5-3=2

Let n=2

S2=5(2)^2-3×2

=5×4 - 6=20-6=14

Let n=3

S3=5(3)^2-3×3

=5×9-9=45-9=36

Now,

a1=S1

a1=2

a2=S2 - S1

=14-2=12

a3=S3 - S2

=36-14=22

Therefore, AP=a1,a2,a3

AP=2,12,22

NOW,

a=2 , d=12-2=10

an=a+(n-1)×d

a16=2+(16-1)×10

=2+15×10

=2+150

a16=152

HOPE IT HELPS!!