Writeanequationtodescribethesequencebelow.Usentorepresentthepositionofaterminthesequence,wheren = 1forthefirstterm.

2 , 10 , 50 , ...

Write your answer using decimals and integers.

an = _(_)^ n^ -^ 1

1 answer

To find an equation for the sequence \(2, 10, 50, \ldots\), we first examine the pattern of the terms.

  1. Identifying the Terms:

    • \(a_1 = 2\)
    • \(a_2 = 10\)
    • \(a_3 = 50\)
  2. Finding a Pattern:

    • We can observe the relationship between the terms:
      • \(10\) is \(2 \times 5\) (or \(2 \times 5^1\))
      • \(50\) is \(10 \times 5\) (or \(2 \times 5^2\))
      • It appears the terms are \(2\) multiplied by increasing powers of \(5\).
  3. Defining the General Term:

    • The first term can be expressed as:
      • \(a_1 = 2 = 2 \times 5^0\)
      • \(a_2 = 10 = 2 \times 5^1\)
      • \(a_3 = 50 = 2 \times 5^2\)

    This suggests that the \(n\)-th term can be represented as: \[ a_n = 2 \times 5^{n-1} \]

Putting it all together, the equation for the \(n\)-th term in the sequence is:

\[ a_n = 2(5)^{n-1} \]