Question

The length of a rectangle is the width minus 8 units. The area of the rectangle is 9 units. What is the length, in units, of the rectangle?

Answer 1

Let length = l

width = w

Acc. to the question = l = w - 8

Area = 9 units

Area of a rectangle = w ( w - 8) = 9

= w² - 8w = 9

= w² - 8w - 9 = 0

= w² - 9w + w - 9

= w( w - 9 ) 1( w-9)

= (w + 1) ( w-9)

= w = -1, 9

= Since width cannot  be equal to a negative value, w = 9 units

l = w - 8

l = 9 - 8

∴length = 1 unit