Question

if a is 30500 ,Sn is 325000, d is -1500 then find value of n

Answer 1

Answer:

Step-by-step explanation

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

325000= n/2 [30500+(n-1)(-1500)]

650000 = n[30500-1500n+1500]

650000 = n(32000-1500n)

650000 = 32000n - 1500n²

1500n²-32000n + 650000 = 0

500[3n² - 64 + 1300] = 0

3n² - 64 + 1300 =0

Solve this eq