In this activity, you will rearrange and solve a rational equation and find and use the inverse of a rational equation. As we’ve seen, for a circuit with two resistors arranged in parallel, we can calculate the total resistance in the circuit, RT , in ohms, with this equation.

1.Rewrite the equation to represent the resistance of resistor 2, R2 , in terms of RT and R1.
A. R2=RTR1/R1-1
B. R2= R1 + R2/RT R1
C. R2=RT - R1/RTR1
D. R2= RT R1/R1-RT
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The total resistance in a circuit with two parallel resistors is 2 ohms and R1 is 6 ohms.
Using the equation for R2, in terms of RT and R1, what is R2?
R2 is ? ohms
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2.Lightbulbs act as resistors. Janine is building a circuit that contains two lightbulbs in parallel. One of the lightbulbs has a resistance of 120 ohms, but the resistance of the second lightbulb is unknown. She models the total resistance in the circuit, t, with this equation, in which r represents the resistance of the second lightbulb.
t=120r/r+120
Find the inverse of Janine’s equation.
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Janine determines that the total resistance in her circuit is 80 ohms. Using the inverse equation modeling this situation, find the resistance of the second lightbulb.

The resistance of the second lightbulb is ? ohms