1 + 2 x 3 + 3 x 9 + 4 x 27 + ... + 9 + 38 what does ... mean?
N nowayitsmel New member Joined Jan 25, 2008 Messages 6 Jan 25, 2008 #1 1 + 2 x 3 + 3 x 9 + 4 x 27 + ... + 9 + 38 what does ... mean?
L Loren Senior Member Joined Aug 28, 2007 Messages 1,299 Jan 26, 2008 #2 Re: evaluate It means to continue the pattern.
S soroban Elite Member Joined Jan 28, 2005 Messages 5,586 Jan 26, 2008 #3 Hello, nowayitsmel! \(\displaystyle \text{Evaluate: }\;1 + 2\cdot3 + 3\cdot9 + 4\cdot27 + \hdots + 9\cdot3^8\) Click to expand... The 'three dots' mean: "and so on in the same manner". \(\displaystyle \text{We have: }\;S \;=\;1\cdot3^0 + 2\cdot3^1 + 3\cdot3^2 + 4\cdot3^3 + 5\cdot3^4 + 6\cdot3^5 + 7\cdot3^6 + 8\cdot3^7 + 9\cdot3^8\) I suppose they expect us to find the sum by some algebraic method. . . I did . . . and it's much easier to do the arithmetic.
Hello, nowayitsmel! \(\displaystyle \text{Evaluate: }\;1 + 2\cdot3 + 3\cdot9 + 4\cdot27 + \hdots + 9\cdot3^8\) Click to expand... The 'three dots' mean: "and so on in the same manner". \(\displaystyle \text{We have: }\;S \;=\;1\cdot3^0 + 2\cdot3^1 + 3\cdot3^2 + 4\cdot3^3 + 5\cdot3^4 + 6\cdot3^5 + 7\cdot3^6 + 8\cdot3^7 + 9\cdot3^8\) I suppose they expect us to find the sum by some algebraic method. . . I did . . . and it's much easier to do the arithmetic.
N nowayitsmel New member Joined Jan 25, 2008 Messages 6 Jan 26, 2008 #4 thank you both soo much I couldn't have done it without you.