Answer :

To solve the subtraction problem [tex]\( 2.8 \cdot 10^{-3} - 0.00065 \)[/tex] and express the answer in scientific notation, follow these steps:

1. Convert the Numbers to Standard Form:
- The number [tex]\( 2.8 \cdot 10^{-3} \)[/tex] is already in scientific notation and can be written as [tex]\( 0.0028 \)[/tex] in standard decimal form.
- The number [tex]\( 0.00065 \)[/tex] does not need conversion as it is already in standard decimal form.

2. Perform the Subtraction:
Subtract the two numbers in their standard decimal form:
[tex]\[ 0.0028 - 0.00065 = 0.00215 \][/tex]

3. Convert the Result to Scientific Notation:
Now, convert the result back into scientific notation:
- [tex]\( 0.00215 \)[/tex] can be written as [tex]\( 2.15 \cdot 10^{-3} \)[/tex] in scientific notation (since [tex]\( 0.00215 = 2.15 \times 10^{-3} \)[/tex]).

Therefore, the final answer in scientific notation is:
[tex]\[ 2.8 \cdot 10^{-3} - 0.00065 = 2.15 \cdot 10^{-3} \][/tex]