Question 430175: The area of a rectangle is 45 square cm. If the length is 4 cm greater than the width, what are the dimension of the rectangle?
Answer by algebrahouse.com(1659)   (Show Source):
You can put this solution on YOUR website! "The area of a rectangle is 45 square cm. If the length is 4 cm greater than the width, what are the dimension of the rectangle?"
x = width
x + 4 = length {length is 4 greater than width}
Area of a rectangle is length x width
x(x + 4) = 45 {area = length x width}
x² + 4x = 45 {used distributive property}
x² + 4x - 45 = 0 {subtracted 45 from both sides}
(x + 9)(x - 5) = 0 {factored into two binomials}
x + 9 = 0 or x - 5 = 0 {set each factor equal to 0}
x = -9 or x = 5 {solved each equation for x}
**x {the width} cannot be negative**
x = 5
x + 4 = 9 {substituted 5, in for x, into x + 4}
width = 5cm and length = 9cm
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