You can put this solution on YOUR website! help me to find the sum 3+11+19+...+787.
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Find "n":
787 = a + (n-1)d when a = 3 ; d = 8
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787 = 3 + (n-1)8
784 = (n-1)8
n-1 = 98
n = 99
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Sum = (n/2)(a+last)
Sum = (99/2)(3+787)
Sum = 39105
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Cheers,
Stan H.
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