The length of a rectangle is four meters less than twice its width.

If the area of the rectangle is 96 m^2, what is the length and the width?
Using trial and error, if the area is 96 m^2, then the length and width are

1 answer

Let the width of the rectangle be \( w \) meters. According to the problem, the length \( l \) of the rectangle is given by:

\[ l = 2w - 4 \]

The area \( A \) of the rectangle is given by the formula:

\[ A = l \times w \]

Substituting the expression for the length into the area formula:

\[ 96 = (2w - 4) \times w \]

Expanding this equation:

\[ 96 = 2w^2 - 4w \]

Rearranging it into a standard quadratic equation format:

\[ 2w^2 - 4w - 96 = 0 \]

Dividing the entire equation by 2 for simplicity:

\[ w^2 - 2w - 48 = 0 \]

Now, we will solve this quadratic equation using the trial and error method. We are looking for two numbers that multiply to \(-48\) and add to \(-2\).

Trying some factors of \(-48\):

  • \(6\) and \(-8\) multiply to \(-48\) and add to \(-2\).

Thus, we can factor the equation as follows:

\[ (w - 8)(w + 6) = 0 \]

Setting each factor to zero gives:

\[ w - 8 = 0 \quad \Rightarrow \quad w = 8 \] \[ w + 6 = 0 \quad \Rightarrow \quad w = -6 \quad \text{(not valid since width cannot be negative)} \]

So, the width \( w \) is \( 8 \) meters. Now we can find the length \( l \):

\[ l = 2w - 4 = 2(8) - 4 = 16 - 4 = 12 , \text{meters} \]

Therefore, the dimensions of the rectangle are:

Width: \( 8 \) meters
Length: \( 12 \) meters