Math Problem Statement

Write the first 8

terms of the sequence defined by the recursive formula.

a1

=0

a2

=1

a3

=7

an

=(an−1)/(an−2)+an−3

, for n≥4

Solution

To determine the first 8 terms of the sequence defined by the recursive formula:

Formula:

  1. a1=0a_1 = 0
  2. a2=1a_2 = 1
  3. a3=7a_3 = 7
  4. an=an1an2+an3a_n = \frac{a_{n-1}}{a_{n-2}} + a_{n-3}, for n4n \geq 4.

Step-by-Step Calculation:

Given:

  • a1=0a_1 = 0
  • a2=1a_2 = 1
  • a3=7a_3 = 7

Now, calculate subsequent terms using the recursive formula:

a4a_4:

a4=a3a2+a1=71+0=7a_4 = \frac{a_3}{a_2} + a_1 = \frac{7}{1} + 0 = 7

a5a_5:

a5=a4a3+a2=77+1=1+1=2a_5 = \frac{a_4}{a_3} + a_2 = \frac{7}{7} + 1 = 1 + 1 = 2

a6a_6:

a6=a5a4+a3=27+7=27+497=517a_6 = \frac{a_5}{a_4} + a_3 = \frac{2}{7} + 7 = \frac{2}{7} + \frac{49}{7} = \frac{51}{7}

a7a_7:

a7=a6a5+a4=5172+7=5114+7=5114+9814=14914a_7 = \frac{a_6}{a_5} + a_4 = \frac{\frac{51}{7}}{2} + 7 = \frac{51}{14} + 7 = \frac{51}{14} + \frac{98}{14} = \frac{149}{14}

a8a_8:

a8=a7a6+a5=14914517+2=14914751+2=149102+2=149102+204102=353102a_8 = \frac{a_7}{a_6} + a_5 = \frac{\frac{149}{14}}{\frac{51}{7}} + 2 = \frac{149}{14} \cdot \frac{7}{51} + 2 = \frac{149}{102} + 2 = \frac{149}{102} + \frac{204}{102} = \frac{353}{102}

Final Sequence:

The first 8 terms are: a1=0,a2=1,a3=7,a4=7,a5=2,a6=517,a7=14914,a8=353102.a_1 = 0, \, a_2 = 1, \, a_3 = 7, \, a_4 = 7, \, a_5 = 2, \, a_6 = \frac{51}{7}, \, a_7 = \frac{149}{14}, \, a_8 = \frac{353}{102}.

Would you like more explanation on any step?


Related Questions:

  1. Can you find the general behavior or limit of this sequence?
  2. What happens if a1a_1, a2a_2, or a3a_3 are changed?
  3. How does this sequence relate to convergent/divergent series?
  4. Can we analyze ana_n as nn \to \infty?
  5. Can this be implemented programmatically for larger values of nn?

Tip: For sequences with recursive definitions, substituting terms carefully and simplifying fractions will help avoid calculation errors.

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Math Problem Analysis

Mathematical Concepts

Sequences and Series
Recursive Formulas
Fraction Simplification

Formulas

a1 = 0
a2 = 1
a3 = 7
an = (an−1)/(an−2) + an−3, for n ≥ 4

Theorems

Recursive sequence definition

Suitable Grade Level

Grades 9-12