Answer :

Sure, let's go through the steps to solve the problem [tex]\( 12.1 \times 10^4 \)[/tex]:

1. Understand the components of the multiplication:
- [tex]\( 12.1 \)[/tex] is the number we want to multiply.
- [tex]\( 10^4 \)[/tex] is the power of 10, which means [tex]\( 10 \times 10 \times 10 \times 10 \)[/tex] or 10,000.

2. Setup the multiplication:
- We are multiplying [tex]\( 12.1 \)[/tex] by [tex]\( 10,000 \)[/tex].

3. Perform the multiplication:
- To multiply by [tex]\( 10,000 \)[/tex], you can move the decimal point in [tex]\( 12.1 \)[/tex] four places to the right because [tex]\( 10^4 \)[/tex] has four zeros.

4. Shift the decimal point:
- Start with [tex]\( 12.1 \)[/tex].
- Move the decimal point four places to the right:
- Move one place: [tex]\( 121. \)[/tex] (equivalent to [tex]\( 121.0 \)[/tex])
- Move another place: [tex]\( 1210. \)[/tex] (equivalent to [tex]\( 1210.0 \)[/tex])
- Move a third place: [tex]\( 12100. \)[/tex] (equivalent to [tex]\( 12100.0 \)[/tex])
- Move a fourth place: [tex]\( 121000. \)[/tex] (equivalent to [tex]\( 121000.0 \)[/tex])

So, after moving the decimal point four places to the right, we get [tex]\( 121000.0 \)[/tex].

5. Final result:
- The product of [tex]\( 12.1 \)[/tex] and [tex]\( 10^4 \)[/tex] is [tex]\( 121000.0 \)[/tex], which can be written as [tex]\( 121,000 \)[/tex].

Therefore, the correct answer is:
[tex]\[ 121,000 \][/tex]