Does the expression for length = 7x^3 - 11x^2 ??

Question

The width w of a rectangular swimming pool is 7x^2. The area A of the pool is 7x^3 – 42x^2. What is an expression for the length of the pool? 

 

Does the expression for length = 7x^3 - 11x^2 ??

 

Answer 1

A = length · width

 

7x³ - 42x² = L(7x²)          Factor left side

7x²(x - 6) = L(7x²)           Divide both sides by 7x²

x - 6 = L

 

The length of the pool is x - 6. 

 

Note: Length is always longer than width. Although the algebra is correct, it is doubtful that x - 6 is greater than 7x².

Answer 2

A=l*w

7x^3-42x^2=l*(7x^2)

l=(7x^3-42x^2)/(7x^2)

l=(7x^3)/(7x^2)-(42x^2)/(7x^2)

l=x-6