Explain how to write 50,000 using exponents

For this case we have the following number:
 
 To rewrite the number we can use the exponential notation as follows:
 
 Where,
 a: is the first digit of the number from left to right
 b: is the number of times you must move the decimal to simplify the expression.
 So we have to use the definition:
 
 
 Using scientific notation we have:
 

5(2a-5+b). xbox xboxxbx xb

How am i goonna know explain