Math Problem Statement

Find the general term and the missing terms of each sequence: 1, square root of 3, square root of 7, _, _

Solution

Let's find the general term of the sequence 1,3,7,1, \sqrt{3}, \sqrt{7}, \dots and determine the missing terms.

Step 1: Identify the pattern.

The sequence begins with:

  • a1=1a_1 = 1
  • a2=3a_2 = \sqrt{3}
  • a3=7a_3 = \sqrt{7}

Let's define a general term for the sequence. Assume the general term takes the form an=An+Ba_n = \sqrt{An + B}, where AA and BB are constants we need to determine.

Step 2: Set up equations based on known terms.

From the given sequence, we have:

  1. a1=A(1)+B=1a_1 = \sqrt{A(1) + B} = 1
  2. a2=A(2)+B=3a_2 = \sqrt{A(2) + B} = \sqrt{3}
  3. a3=A(3)+B=7a_3 = \sqrt{A(3) + B} = \sqrt{7}

We can square both sides of each equation to eliminate the square roots:

  1. A(1)+B=12=1A(1) + B = 1^2 = 1
  2. A(2)+B=(3)2=3A(2) + B = (\sqrt{3})^2 = 3
  3. A(3)+B=(7)2=7A(3) + B = (\sqrt{7})^2 = 7

This results in the system of equations:

  1. A+B=1A + B = 1
  2. 2A+B=32A + B = 3
  3. 3A+B=73A + B = 7

Step 3: Solve the system of equations.

We can subtract the first equation from the second and third equations to eliminate BB:

  • (2A+B)(A+B)=31(2A + B) - (A + B) = 3 - 1
  • A=2A = 2

Now subtract the second equation from the third:

  • (3A+B)(2A+B)=73(3A + B) - (2A + B) = 7 - 3
  • A=4A = 4

Using A=2A = 2, substitute into the first equation:

  • 2+B=12 + B = 1
  • B=1B = -1

Step 4: General term.

Now that we have A=2A = 2 and B=1B = -1, the general term is: an=2n1a_n = \sqrt{2n - 1}

Step 5: Find the missing terms.

Now, using the general term formula an=2n1a_n = \sqrt{2n - 1}, let's calculate the next terms:

  • a4=2(4)1=81=7a_4 = \sqrt{2(4) - 1} = \sqrt{8 - 1} = \sqrt{7}
  • a5=2(5)1=101=3a_5 = \sqrt{2(5) - 1} = \sqrt{10 - 1} = 3

Final Sequence:

The full sequence is: 1,3,7,7,31, \sqrt{3}, \sqrt{7}, \sqrt{7}, 3

Would you like further clarification or a more detailed explanation on any part of this process?

Follow-up Questions:

  1. How would you approach solving a different sequence problem with non-square root terms?
  2. Can you derive the general term if the sequence starts with different values?
  3. How do arithmetic sequences differ from this type of sequence?
  4. How would the general term change if the difference between terms was constant?
  5. What if the general term involves a cubic or higher-degree polynomial?

Tip:

When analyzing sequences, always check if differences between consecutive terms follow a recognizable pattern, such as arithmetic or geometric, or involve square roots or other functions.

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Math Problem Analysis

Mathematical Concepts

Sequences
Square Roots
General Term

Formulas

General term of a sequence

Theorems

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Suitable Grade Level

Grades 10-12