Chapter 4.7, Problem 5WE

To determine

To solve the equation $I=Prt$ , for P .

Answer to Problem 5WE

  $P=\frac{I}{rt},r,t\ne 0$

Explanation of Solution

Given:

The equation, $I=Prt$

Concept Used:

• To get rid of a number in addition from one side, subtract the same number from both sides of equal sign.
• To get rid of a number in subtraction from one side, add the same number both sides of equal sign.
• To get rid of a number in multiplication from one side, divide the same number from both sides of equal sign.
• To get rid of a number in division from one side, multiply the same number both sides of equal sign.

Calculation:

To solve the given equation $I=Prt$ for P , isolate the variable term P on one side by performing some basic algebraic operations to get rid of the other numbers and terms associated with it.

Here to isolate P on left side, divide both sides by $rt$ and simplify further as shown below,

  $\begin{array}{c}I=Prt\\ \frac{I}{rt}=\frac{Prt}{rt}\\ \frac{I}{rt}=P\\ \Rightarrow P=\frac{I}{rt}\end{array}$

Thus, on solving for the indicated variable it gives $P=\frac{I}{rt}$ .

Since it is a rational expression after solving for the indicated variable, so the denominator should not be zero. That is, $r,t\ne 0$ .