Math Problem Statement

Find the two geometric means between 2 and 16

Solution

To find the two geometric means between 2 and 16, we can use the formula for the geometric mean in a sequence. If we have a sequence a1,a2,a3,a4a_1, a_2, a_3, a_4 where a1=2a_1 = 2, a4=16a_4 = 16, and a2a_2 and a3a_3 are the geometric means, the relationship between consecutive terms in a geometric sequence is given by:

Common ratio=r=an+1an\text{Common ratio} = r = \frac{a_{n+1}}{a_n}

Since there are two geometric means, the sequence can be written as:

2,a2,a3,162, a_2, a_3, 16

Let the common ratio be rr. Then:

a2=2ra_2 = 2r a3=2r2a_3 = 2r^2 16=2r316 = 2r^3

Now, solve for rr:

r3=162=8r^3 = \frac{16}{2} = 8

r=83=2r = \sqrt[3]{8} = 2

Now, we can find the geometric means:

a2=2r=2×2=4a_2 = 2r = 2 \times 2 = 4

a3=2r2=2×4=8a_3 = 2r^2 = 2 \times 4 = 8

So, the two geometric means between 2 and 16 are 4 and 8.

Would you like more details or have any questions?


Here are 5 related questions you might find interesting:

  1. What is the geometric mean of two numbers?
  2. How do you find the nth term in a geometric sequence?
  3. Can geometric means be negative?
  4. How do you solve for the common ratio in a geometric sequence?
  5. What is the difference between arithmetic and geometric sequences?

Tip: The geometric mean is always greater than or equal to the arithmetic mean if all the numbers in the sequence are positive.

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Math Problem Analysis

Mathematical Concepts

Geometric Sequence
Geometric Mean
Ratios

Formulas

Common ratio formula: r = a_(n+1)/a_n
Geometric mean formula: a_n = a_1 * r^(n-1)

Theorems

Geometric sequence properties

Suitable Grade Level

Grades 9-11