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Evaluate k=091000xk=5×60×1000\sum_{k=0}^{9}1000x^{k}=5\times60\times1000

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Q. Evaluate k=091000xk=5×60×1000\sum_{k=0}^{9}1000x^{k}=5\times60\times1000
  1. Identify Geometric Series: The given series is a geometric series with the first term a=1000a = 1000 (when k=0k=0) and the common ratio r=xr = x (since each term is xx times the previous term). The sum of a finite geometric series can be found using the formula Sn=a(1rn)(1r)S_n = \frac{a(1 - r^n)}{(1 - r)}, where nn is the number of terms.
  2. Calculate Number of Terms: In this case, the number of terms nn is 1010 (from k=0k=0 to k=9k=9). We can plug the values into the formula to find the sum: S10=1000(1x10)(1x)S_{10} = \frac{1000(1 - x^{10})}{(1 - x)}.
  3. Use Sum Formula: We are given that the sum of the series is equal to 5×60×10005\times60\times1000. This means that S10=5×60×1000S_{10} = 5\times60\times1000.
  4. Set Up Equation: Now we can set up the equation 1000(1x10)/(1x)=5×60×10001000(1 - x^{10}) / (1 - x) = 5\times60\times1000 and solve for xx.
  5. Simplify Right Side: First, we simplify the right side of the equation: 5×60×1000=300,0005\times60\times1000 = 300,000.
  6. Divide by 10001000: Now the equation is 1000(1x10)/(1x)=300,0001000(1 - x^{10}) / (1 - x) = 300,000. To simplify further, we can divide both sides by 10001000, which gives us (1x10)/(1x)=300(1 - x^{10}) / (1 - x) = 300.
  7. Consider x=1x=1: This equation is not straightforward to solve algebraically for xx, as it involves a polynomial of degree 1010. However, we can notice that if x=1x=1, the denominator becomes zero, which is not allowed. Therefore, xx cannot be 11. If xx were to be 11, the left side of the equation would be undefined, which cannot equal 300300. This suggests that there might be an error in the problem statement or a misunderstanding of the problem as it stands.

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