How Do I Find The First Term In Geometric Sequence? Best Explained Answer Gets 10 Points?

1. Steven Angulo Says

   Since the payments reduce each month by the same percentage, let’s call “x” the constant number that multiplied by the payment of a month gives you the payment of the following month. Since they paid $900 in the second month, in the third month they paid 900x, like this:
   (900x) = third month
   (900x)x = fourth month = 729
   900x^2 = 729
   x^2 = 729/900 = 0.81
   x = 0.9
   With this number, we can see that:
   Fifth month = 729*0.9 = $656.1
   Sixth month = 656.1*0.9 = $590.49 (consistent with what the problem says)
   How much did they pay in the first month? Let’s call “y” that amount. Then:
   y*0.9 = $900 (second month)
   y = 900/0.9
   y = 1000
   So they paid exactly $1000 in the first month.
   I hope this helps!

2. Mike G Says

   nth term of a geometric series is
   ar^(n-1) where a = first term and r = ratio
   second term n=2
   ar^1 = 900
   ar^(4-1) = 729
   r^2 = 729/900
   r = 0.9
   a = 900/0.9 = 1000
   They paid $1000 in the first month.

3. wirehawk Says

   The difference between two payments is 19%.
   $900 x 19% = $171
   $900 + 171 = $1,071

4. 45363762 Says

   simple

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