Math Problem Statement

The length of a rectangle is represented by the function L(x) = 4x. The width of that same rectangle is represented by the function W(x) = 7x2 − 4x + 2. Which of the following shows the area of the rectangle in terms of x?

(L + W)(x) = 7x2 + 2 (L + W)(x) = 7x2 − 8x + 2 (L ⋅ W)(x) = 28x3 − 16x2 + 8x (L ⋅ W)(x) = 28x3 − 4x + 2

Solution

The area A(x)A(x) of a rectangle is given by multiplying its length and width:

A(x)=L(x)W(x)A(x) = L(x) \cdot W(x)

Given functions:

L(x)=4xL(x) = 4x W(x)=7x24x+2W(x) = 7x^2 - 4x + 2

Now, multiply:

A(x)=(4x)(7x24x+2)A(x) = (4x) \cdot (7x^2 - 4x + 2)

Distribute 4x4x:

A(x)=4x7x2+4x(4x)+4x2A(x) = 4x \cdot 7x^2 + 4x \cdot (-4x) + 4x \cdot 2

A(x)=28x316x2+8xA(x) = 28x^3 - 16x^2 + 8x

Thus, the correct answer is:

(LW)(x)=28x316x2+8x\boxed{(L \cdot W)(x) = 28x^3 - 16x^2 + 8x}


Would you like a breakdown of any specific step?

Here are 5 related questions to expand your understanding:

  1. How do you find the perimeter of the rectangle given L(x)L(x) and W(x)W(x)?
  2. What happens to the area when x=0x = 0 or x=1x = 1?
  3. How do you determine the domain of the area function A(x)A(x)?
  4. How would you express the area as a function of a different variable, say tt, if x=t2x = t^2?
  5. How does the rate of change of the area function relate to its derivative?

Tip:

When multiplying polynomials, distribute each term carefully and ensure you combine like terms correctly!

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Math Problem Analysis

Mathematical Concepts

Algebra
Polynomials
Area of a Rectangle

Formulas

Area of a rectangle: A(x) = L(x) * W(x)

Theorems

Distributive Property

Suitable Grade Level

Grades 8-10