Math Problem Statement

The first two terms of a geometric sequence are 4 and 5.8. Find the third term. Round answer to four places after the decimal point.

Third term =

Solution

To find the third term of a geometric sequence, we need to follow these steps:

  1. The first term a1=4a_1 = 4.

  2. The second term a2=5.8a_2 = 5.8.

  3. A geometric sequence follows the relationship: an=a1rn1a_n = a_1 \cdot r^{n-1} where rr is the common ratio between consecutive terms.

  4. To find rr, we can use the ratio of the second term to the first term: r=a2a1=5.84=1.45r = \frac{a_2}{a_1} = \frac{5.8}{4} = 1.45

  5. Now, we can find the third term a3a_3 using the formula: a3=a1r2a_3 = a_1 \cdot r^2 Substituting the values: a3=4(1.45)2a_3 = 4 \cdot (1.45)^2

Let's calculate the third term.The third term of the geometric sequence is 8.41008.4100, rounded to four decimal places.

Would you like further details or explanations? Here are five related questions for practice:

  1. What is the fourth term of the sequence?
  2. How would you find the 10th term of this geometric sequence?
  3. If the first term was 3 instead of 4, what would the common ratio be?
  4. How do you derive the formula for the nth term in a geometric sequence?
  5. What is the sum of the first three terms of this geometric sequence?

Tip: In geometric sequences, the common ratio can be found by dividing any term by the previous one!

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Math Problem Analysis

Mathematical Concepts

Geometric Sequences
Ratios
Exponents

Formulas

General formula for the nth term of a geometric sequence: a_n = a_1 * r^(n-1)
Common ratio formula: r = a_2 / a_1

Theorems

None required

Suitable Grade Level

Grades 8-10