SOLUTION: The length of a rectangle is one foot less then three times the width. Find the length and width of the area is 30 square feet

Question 447077: The length of a rectangle is one foot less then three times the width. Find the length and width of the area is 30 square feet
Answer by chriswen(106) (Show Source): You can put this solution on YOUR website!
Let x ft be the width of the rectangle.
Let 3x-1 ft be the length of the rectangle.
...
l*w=A
(3x-1)(x)=30
3x^2-x=30
3x^2-x-30=0

Solved by pluggable solver: SOLVE quadratic equation with variable

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=361 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 3.33333333333333, -3. Here's your graph:

x must be positive.
x=3.33
3x-1=9
Therefore, the rectangle is 3.33 ft by 9 ft.
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