Answer: Choice A) -312,500
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The long way to find the answer is to multiply each term by -5 until you've generated 8 terms total.
4 is the first term
-20 is the second term (4 times -5 = -20)
100 is the third term (-20 times -5 = 100)
100 times -5 = -500 which is the fourth term
-500 times -5 = 2500 which is the fifth term
2500 times -5 = -12500 which is the sixth term
-12500 times -5 = 62500 which is the seventh term
62500 times -5 = -312500 which is the eigth term
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A shortcut is to use the formula below
a(n) = a*(r)^(n-1)
Plug in a = 4, r = -5 and n = 8
a(n) = a*(r)^(n-1)
a(8) = 4*(-5)^(8-1)
a(8) = 4*(-5)^7
a(8) = 4*(-78125)
a(8) = -312,500
and we get the same answer
