SOLUTION: given a1=94 the common difference is -3, find n so that sn=805. (hint: you will use -b square root b squared -4ac divided by 2a to solve for n)
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-> SOLUTION: given a1=94 the common difference is -3, find n so that sn=805. (hint: you will use -b square root b squared -4ac divided by 2a to solve for n)
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Question 860723: given a1=94 the common difference is -3, find n so that sn=805. (hint: you will use -b square root b squared -4ac divided by 2a to solve for n) Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website! S = ½(2a + (n-1)d)n
805 = ½(2*94 + (n-1)(-3))n
805 = (191 n)/2-(3 n^2)/2
n = 10
n = 161/3
n must be a whole number.
so n=10
