Given : The Area of the Rectangle = x⁴ - 100
We know that : (a + b)(a - b) = a² - b²
⇒ x⁴ - 100 can be written as : (x²)² - (10)²
⇒ (x²)² - (10)² can be written as : (x² + 10)(x² - 10)
We know that, Area of a Rectangle is given by : Length × Width
Comparing (x² + 10)(x² - 10) with Area of the Rectangle formula, We can notice that :
⊕ Length = x² + 10
⊕ Width = x² - 10
Given : Length of the Rectangle is 20 units more than Width
⇒ Width + 20 = Length
⇒ x² - 10 + 20 = x² + 10
⇒ x² + 10 = x² + 10
Answer : x² - 10 represents the width of the rectangle. Because the area expression can be rewritten as (x² - 10)(x² + 10) which equals
(x² - 10)((x² - 10) + 20)
⇒ Option A
