SOLUTION: Find the difference between the sums to ten terms of the AP and GP whose first two terms are -2 and 4.

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Question 1198088: Find the difference between the sums to ten terms of the AP and GP whose first two terms are -2 and 4.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi  
AP:  a%5Bn%5D=a%5B1%5D%2B%28n-1%29%2Ad, S%5Bn%5D=+%28n%2F2%29%282%2Aa%5B1%5D%2B+%28n-1%29d%29
a%5B2%5D+=+-2+%2B+d+=+4, d = 6 , S%5B10%5D=+%2810%2F2%29%282%2A%28-2%29%2B+9%2A6%29 = 250

GP: a%5Bn%5D+=+a%5B1%5D%2Ar%5E%28n-1%29,    S%28n%29+=+a%5B1%5D%28%281-r%5En%29%2F%281-r%29%29
 a%5B2%5D+=+%28-2%29r+=+4, r = -2,   S%2810%29+=+%28-2%29%28%281-%28-2%29%5E10%29%2F%283%29%29 = 682

Wish You the Best in your Studies.