Problem:
The heat H developed in an electric resistor varies jointly as the time t and the square of the current i in the resistor. If H0 (the zero is slightly below the H) joules of heat are developed in t0 seconds (the zero is slightly below the t) with i0 amperes (the zero is slightly below the i) passing through the resistor, how much heat is developed if the time is halved and the current is doubled?