You complete 3cm of a necklace in a hour each hour after the first you triple the length of the necklace write an expressions using exponents for the length of the necklace after 3 hours then find the length

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after x hours, the length is

3*3^x

To find the length of the necklace after 3 hours, we can use the following expression:

Length = 3 cm + (3 cm) * (3)^3

Here's a step-by-step breakdown of how to derive this expression:

1. In the first hour, you complete 3 cm of the necklace (as stated in the problem).

2. In the second hour, you triple the length of the necklace. This means the length after the second hour is (3 cm) * 3 = 9 cm.

3. In the third hour, you again triple the length of the necklace. This means the length after the third hour is (3 cm) * 3 * 3 = 27 cm.

4. To generalize the expression for finding the length after any given number of hours, we can use (3 cm) * (3)^n, where 'n' represents the number of hours after the first hour.

Therefore, substituting 'n' with 3 (since we want to find the length after 3 hours), the expression becomes:

Length = 3 cm + (3 cm) * (3)^3
= 3 cm + (3 cm) * 27
= 3 cm + 81 cm
= 84 cm

So, the length of the necklace after 3 hours is 84 cm.