Accounting ( please with the formula and the explanation) take your time

please don't copy-paste from another expert I already saw all their answer.

if you will answer me don't forget b and c because is very important

Exercise 1:

On December 31st , 2011, a company acquired a new research quantum computer. The cost of the computer was 6,000.000 with a residual value of 1,000,000 at the end of its estimated useful lifetime of 4 years.

Instructions

a. Prepare a complete depreciation schedule, beginning with the calendar year 2011, under each of the methods listed below (with fractional years rounded to the nearest whole month):

1. Straight-line
2. 200 percent declining-balance
3. 150 percent declining-balance

b. Assume that a company sells the asset on December 31, 2014, for 2,000,000 cash. Compute the resulting gain or loss from this sale under each of the depreciation methods used in part a.

c. Which of the methods would you advise to use and why?