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

If the area of the rectangle is 96 square meters, what is the length and the width?
An expression for the length of the rectangle in terms of the width would be __________________.
The formula for the area of a rectangle is ___________.
Using trail and error, if the area is 96m^2, then the length and width are ___________.
Answers:
L=2w-4
W=2l-4
Area=1/2(l•w)
L=12&w=8
Area=2l+2w
L=24&w=4
L=4-2w
Area=l•w
L=8&w=12
L=4&w=24

1 answer

Let's break the problem down step by step.

  1. Finding an Expression for the Length in terms of Width: We know that the length (L) of the rectangle is four meters less than twice its width (W). We can express this relationship mathematically: \[ L = 2W - 4 \]

  2. Formula for the Area of a Rectangle: The area (A) of a rectangle can be calculated using the formula: \[ \text{Area} = L \cdot W \]

  3. Solving for Length and Width: We know that the area of the rectangle is 96 square meters: \[ L \cdot W = 96 \]

    Substituting the expression for L from step 1 into the area formula: \[ (2W - 4) \cdot W = 96 \] Expanding this gives: \[ 2W^2 - 4W = 96 \] Rearranging to form a standard quadratic equation: \[ 2W^2 - 4W - 96 = 0 \] Dividing the entire equation by 2 simplifies it: \[ W^2 - 2W - 48 = 0 \]

  4. Factoring the Quadratic Equation: We can factor this quadratic: \[ (W - 8)(W + 6) = 0 \] This gives us two potential solutions for W:

    • \( W = 8 \) (taking the positive solution, as width cannot be negative)
    • \( W = -6 \) (not applicable since width cannot be negative)
  5. Finding the Length: Now substituting \( W = 8 \) back into the equation for L: \[ L = 2(8) - 4 = 16 - 4 = 12 \]

Thus, the final dimensions of the rectangle are:

  • Length: 12 meters
  • Width: 8 meters

Summary Answers:

  • An expression for the length of the rectangle in terms of the width would be L = 2W - 4.
  • The formula for the area of a rectangle is Area = L • W.
  • Using trial and error, if the area is 96 m², then the length and width are L = 12 m & W = 8 m.

So, the final correct entries are:

  • L = 2W - 4
  • Area = L • W
  • L = 12 & W = 8