Question

A student was asked to use the formula For the perimeter Of a rectangle.P =2l+ 2w, To Solve for L. The student came up with the answer P- 2w = 2l. what error did he make ? Explain.

Answer 1

The formula for the perimeter of a rectangle is given by

$P=2l+2w$

The student was asked to solve for length (l) and he came up with the following answer

$P-2w=2l$

Notice that he did not fully solved the equation for length (l)

He needs to separate the length (l) by dividing both sides by 2

$\begin{gathered} \frac{P-2w}{2}=\frac{2l}{2} \\ \frac{P-2w}{2}=l \\ l=\frac{P-2w}{2} \end{gathered}$

Now, the equation is solved for length (l)