SOLUTION: find the sum 2+(-6)+18 + ......(-486)

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Question 1152056: find the sum 2+(-6)+18 + ......(-486)

Found 2 solutions by MathLover1, MathTherapy:
Answer by MathLover1(20850)   (Show Source): You can put this solution on YOUR website!
find the sum + ......
=> common ratio is
first term:
last term:

the number of terms in this sequence is:




.........
............exponents with same base, so





then, the sum of all terms is:
















Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!

find the sum 2+(-6)+18 + ......(-486)
A seen this is a G.P.
Sum of a G.P.: , where:

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