Algebra 2A Semester Exam

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Question
Approximate 1935√
, correct to one decimal place, by using a sequence of values that gets closer and closer to 5–√
.(1 point)

1 answer

To approximate \( \sqrt{1935} \) using a sequence of values that gets closer to \( 5 \), you can use the method of successive approximations. Here’s how to approach it:

  1. Understand that \( \sqrt{1935} \) is between two integers. Since \( 1935 \) is between \( 1936 \) and \( 1930 \), we know that \( \sqrt{1935} \) will be between \( 44 \) (since \( 44^2 = 1936 \)) and \( 43 \) (since \( 43^2 = 1849 \)).

  2. Start with an initial guess. A good starting point might be \( 44 \), because it is close to the upper bound.

  3. Use the average of your guess and the result of dividing the original number by your guess. This is known as the Babylonian method (also known as Heron's method).

    • Let’s say your initial guess \( x_0 = 44 \).
    • Calculate a new guess \( x_1 = \frac{x_0 + \frac{1935}{x_0}}{2} \).
    • Substitute \( x_0 = 44 \):
      • Calculate \( \frac{1935}{44} \approx 43.97727 \).
      • Therefore, \( x_1 = \frac{44 + 43.97727}{2} \approx 43.98864 \).
  4. Repeat the process with \( x_1 \):

    • Now, take \( x_1 = 43.98864 \) as your next guess.
    • Calculate \( x_2 = \frac{x_1 + \frac{1935}{x_1}}{2} \).
    • Substitute \( x_1 \):
      • Calculate \( \frac{1935}{43.98864} \approx 43.99843 \).
      • Therefore, \( x_2 = \frac{43.98864 + 43.99843}{2} \approx 43.99354 \).
  5. Continue this process until the guesses converge. Each iteration should get you closer to \( \sqrt{1935} \).

  6. For practical purposes, we can also quickly calculate:

    • \( 44^2 = 1936 \)
    • \( 43^2 = 1849 \)

    Thus, we can narrow it down quickly:

    • Approximating further:
      • \( 43.99^2 \approx 1931.9601 \) (too low)
      • \( 44.01^2 \approx 1934.4801 \) (too low)
      • \( 44.05^2 \approx 1936.0025 \) (too high)

    From this, we conclude that the approximation for \( \sqrt{1935} \) is about \( 44.0 \).

Final answer, correct to one decimal place: 44.0.