Three correct expressions for electric power dissipated in a resistor are P = IV, P = I^2 R, and P = V^2 / R. Which of the following expressions for electric power is INCORRECT?

1. Starting from P = IV and substituting I = V/R from Ohm's law gives P = V^2 / R, expressing power using only voltage and resistance. 2. Starting instead from P = IV and substituting V = IR gives P = I^2 R, expressing power using only current and resistance. 3. P = IV itself is the basic definition of electric power, combining voltage and current directly. 4. That accounts for three of the four listed expressions as valid, source-derived forms of the power equation. 5. The remaining expression, P = V / R^2, does not follow from either substitution: dividing voltage by resistance squared has the wrong units and does not reduce to either derived form. 6. So P = V / R^2 is the incorrect expression among the four. _Source: OpenStax Physics (CC BY 4.0), Ch 19 "Electrical Circuits", section 19.4 Electric Power_