Arithmetic Sequence: Is 29 the nth Term When a₁=1.5 and d=3?

Question

Given a series whose first element is 1.5.

Each element of the series is greater by 3 of its predecessor.

Is the number 29 an element in the series?

If so, please indicate your place in the series.

Video Solution

Solution Steps

00:00 Is the number 29 in the sequence?
00:06 Let's use the sequence formula
00:18 Let's substitute appropriate values according to the given data and solve
00:30 If the value of N is a positive whole number, then the number is a term in the sequence
00:43 Let's properly open the parentheses and multiply by each factor
00:57 We want to isolate N
01:24 The value of N is a decimal number, therefore it's not a term in the sequence
01:28 And this is the solution to the question

Step-by-Step Solution

To determine whether the number 29 is an element of the series, we start by recognizing that the problem involves an arithmetic sequence. In such a sequence, each term is generated by adding a constant difference to the previous term. Here, the first term a1 a_1 is 1.5 1.5 , and the common difference d d is 3 3 .

The formula for the nth term of an arithmetic sequence is given by:

an=a1+(n1)d a_n = a_1 + (n-1) \cdot d

We need to check if 29 is one of the terms of this series, so we set an=29 a_n = 29 and solve for n n :

29=1.5+(n1)3 29 = 1.5 + (n-1) \cdot 3

Subtract 1.5 from both sides:

291.5=(n1)3 29 - 1.5 = (n-1) \cdot 3

27.5=(n1)3 27.5 = (n-1) \cdot 3

Divide both sides by 3 to solve for n1 n - 1 :

n1=27.53 n-1 = \frac{27.5}{3}

n1=9.1666 n-1 = 9.1666\ldots

Add 1 to find n n :

n=10.1666 n = 10.1666\ldots

Since n n is not an integer, the number 29 does not appear as an element in this sequence. Arithmetic sequences only have integer positions for their terms, so n n must be a whole number for 29 to be a term. As a result, the correct answer is:

No

Answer

No