SOLUTION: The length of a rectangle is 13 centimeters less than its width. What are the dimensions of the rectangle if its area is 90 square​ centimeters

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Question 1176501: The length of a rectangle is 13 centimeters less than its width. What are the dimensions of the rectangle if its area is 90 square​ centimeters
Found 3 solutions by Boreal, ikleyn, josgarithmetic:
Answer by Boreal(15235) About Me  (Show Source):
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width is x
length is x-13
area is x^2-13x=90
so x^2-13x-90=0
(x-18)(x+5)=0
x=18 cm only positive root
x-13=5 cm
it is 18 cm wide and 5 cm long

Answer by ikleyn(52754) About Me  (Show Source):
You can put this solution on YOUR website!
.

Let w be the width, in centimeters.

Then the length is  (w+13) cm.


The area equation is


    w*(w+13) = 90.


Solve it MENTALLY by guessing:  w = 5 cm.


Or solve it formally by reducing to a quadratic equation


    w^2 + 13x - 90 = 0.


You may factor


    (w-5)*(w+18) = 0


or use the quadratic formula, on your choice.

Solved.



Answer by josgarithmetic(39613) About Me  (Show Source):
You can put this solution on YOUR website!
x%28x%2B13%29=90-----------x, width, x+13, length

90=9%2A10=3%2A60=6%2A15=2%2A45=highlight%285%29%2Ahighlight%2818%29

Width, 5 cm
Length, 18 cm