Question

a=2, d= 8 और Sn = 90 दिया है। n और an, ज्ञात कीजिए।​

Answer 1

Answer:

given that

a = 2 ,d = 8. ,sn = 90

we know that

S n = n/2{2a+(n -1)d}

90 ×2= n{ 4+(n -1)8}

180= n( 8n - 4)

8n^2-4n - 180 = 0

2n^2 - n - 45= 0

2n^2-10n+ 9n - 45=0

2n(n - 5)+9(n - 5)=0

(n -5)(2n+9)

n has thi solutions

n= 5,-9/2

-9/2 may not possible

so n = 5

SO ,an= 2×5= 10

Hope it helps u

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