400,000(1.05^x)=1,000,000 What would x be in this problem?

400,000(1.05^x)=1,000,000     divide both sides by 400,000

1.05^x = 1000000/40000

1.05^x = 2.5     take the log of both sides

log 1.05^x = log 2.5      and we can write

x log 1.05 = log 2.5        divide both sides by log 1.05

x = log 2.5 / log 1.05  = about 18.78