Math Problem Statement

To get from one term to the next in a sequence, we multiply by 2 and then add 4. The third term in the sequence is 44. What is the first term in the sequence?

Solution

Let's solve this step by step.

  1. Let the first term in the sequence be aa.
  2. According to the problem, to get from one term to the next, we multiply by 2 and then add 4.

So, we have the following relationships:

  • Second term: a2+4a \cdot 2 + 4
  • Third term: (a2+4)2+4(a \cdot 2 + 4) \cdot 2 + 4

We are given that the third term is 44.

Step-by-Step Calculation

  1. Starting with the second term: Second term=a2+4=2a+4\text{Second term} = a \cdot 2 + 4 = 2a + 4

  2. Then, the third term (starting from the second term) would be: Third term=(2a+4)2+4\text{Third term} = (2a + 4) \cdot 2 + 4 Simplify this expression: =4a+8+4= 4a + 8 + 4 =4a+12= 4a + 12

  3. We know that the third term is 44, so we can set up the equation: 4a+12=444a + 12 = 44

  4. Solving for aa: 4a=44124a = 44 - 12 4a=324a = 32 a=8a = 8

Answer

The first term in the sequence is 8.

Would you like further details on this solution, or do you have any questions?


Here are 5 related questions to expand your understanding:

  1. What would be the second term in this sequence if the first term is 8?
  2. How would the sequence change if, instead of adding 4, we subtracted 4 after each multiplication?
  3. Can you find a general formula for the nn-th term in this sequence?
  4. What would the fifth term in the sequence be with the first term as 8?
  5. How does the sequence behave if we multiply by a different number each time?

Tip: For sequences with repeated operations (like multiplication and addition), forming equations step-by-step helps solve for unknown terms effectively.

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Math Problem Analysis

Mathematical Concepts

Sequences
Algebra

Formulas

Recursive formula: next term = current term * 2 + 4

Theorems

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Suitable Grade Level

Grade 6-8