Question

The sun of how many terms of the AP 8, 15, 22.
is 1490?​

Answer 1

Answer:

a = 8

d = 15 - 8

= 7

s = 1490

Sn = n/2[2a+(n-1)d]

1490 = n/2[2×8+(n-1)7]

1490 = n/2[ 16+(n-1)7]

7n²+9n-2980=0h

7n²-140n+149(n-20) =0

7n(n-20) + 149(n-20) =0

7n+149 = 0 ; n-20 = 0

7n = -149 ; n =20

n = -149/7

n cannot be negative..

so there are 20 terms

hope it is helpful