Question

1/2x(log)-log(1000)=3

Answer 1

Not sure what your notation means.
If you meant

1/2 log(x) - log(1000) = 3, then
log(√x) - log 1000 = 3
log(√x/1000) = 3
√x/1000 = 10^3 = 1000
√x = 1000*1000 = 10^6
x = 10^12

If I misread it, try correcting the notation and try again, and show us what you think the solution is. Or, you can use my calculations as a model, to get your own answer.