Question

write the first 3 terms of each of the arithematic sequences described below:
1)First term 30;the sum of the first 3 terms is 300
2)First term 30;the sum of the first 4 terms is 300
3)First term 30;the sum of the first 5 terms is 300
4)First term 30;the sum of the first 6 terms is 300​

Answer 1

Step-by-step explanation:

1) a = 30 , S3 = 300 then T1,t2,t3

t1 = 30 , T2 = a+(n-1)d

t2 = 30 + (2-1)d

t2 = 30 +d

so, t3 = 30 + 2d

now, sn = n/2(2a +(n-1)d)

300= 3/2(2(30) +(3-1)d)

300×2/3 = 60+2d

200 = 60 + 2d

d = 70..

T1 = 30+70 = 100

t2 = 30+2(70) = 30+140 = 170..

use this method for remaining 3 sums but take the sn value as given in the question ..like

s4 = 300 then n = 4 ..