Find the sum of a finite geometric sequence from n = 1 to n = 7, using the expression −4(6)n − 1.
111,325
526
782
-223,948

Step-by-step explanation:

The formula of a sum of terms of a gometric sequence:

a₁ - first term

r - common ratio

We have

Calculate a₁. Put n = 1:

Calculate the common ratio:

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step-by-step explanation:

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47 - 90 = 43

43 - 180 = x

x = 137