Rectangle Area Comparison: Finding Difference Between (x+4)(x+3) and (x+5)(x+2)

Question

Look at the rectangles in the diagram below.

Which has a larger area and by how much?

x+4x+4x+4x+5x+5x+5ABx+3x+2

Video Solution

Step-by-Step Solution

Let's calculate the area of each rectangle step by step:

Step 1: Calculate the area of Rectangle A.
- Dimensions are (x+4)(x+4) and (x+3)(x+3).
- The area is calculated as (x+4)×(x+3) (x+4) \times (x+3) .

Expanding this expression using the distributive property, we get:
(x+4)(x+3)=xx+x3+4x+43(x+4)(x+3) = x \cdot x + x \cdot 3 + 4 \cdot x + 4 \cdot 3
x2+3x+4x+12\Rightarrow x^2 + 3x + 4x + 12
x2+7x+12\Rightarrow x^2 + 7x + 12

Step 2: Calculate the area of Rectangle B.
- Dimensions are (x+5)(x+5) and (x+2)(x+2).
- The area is calculated as (x+5)×(x+2) (x+5) \times (x+2) .

Using the distributive property to expand:
(x+5)(x+2)=xx+x2+5x+52(x+5)(x+2) = x \cdot x + x \cdot 2 + 5 \cdot x + 5 \cdot 2
x2+2x+5x+10\Rightarrow x^2 + 2x + 5x + 10
x2+7x+10\Rightarrow x^2 + 7x + 10

Step 3: Compare the areas of Rectangle A and B.
- Area of Rectangle A: x2+7x+12 x^2 + 7x + 12
- Area of Rectangle B: x2+7x+10 x^2 + 7x + 10

Subtract the area of Rectangle B from the area of Rectangle A:
(x2+7x+12)(x2+7x+10)=(x2+7x+12)x27x10 (x^2 + 7x + 12) - (x^2 + 7x + 10) = (x^2 + 7x + 12) - x^2 - 7x - 10
x2x2+7x7x+1210 \Rightarrow x^2 - x^2 + 7x - 7x + 12 - 10
2 \Rightarrow 2

Thus, the area of Rectangle A is larger by 2 2 area units.

The correct answer, therefore, is: The area of rectangle A is larger by 2 area units.

Answer

The area of rectangle A is larger by 2 area units.