The state of X imposes a 1% franchise tax on the net worth of taxpayers incorporated in the state of X, applying a three factor apportionment formula to determine taxable net worth. It imposes a 2% franchise tax on the net worth of taxpayers incorporated outside the state of X, applying the same three factor formula to determine taxable net worth. The higher tax rate imposed on out of state companies is based on the additional cost of the state in auditing and verifying the out of state companies tax returns. Is this tax constitutional?