Hom corporation acquired a computer on january 1, 2011, for $10,000,000. the computer had an estimated useful life of six years and $1,000,000 estimated salvage value. the firm uses the straight-line depreciation method. on january 1, 2013, thom corporation discovers that new technologies make it likely that the computer will last only four years in total and that the estimated salvage value will be only $600,000.what is the amount of depreciation expense for 2013 for this change in depreciable life and salvage value assuming that the change does not represent an impairment loss