SOLUTION: Find the perimeter of the rectangle with length of 3x, width of 2x-1 and area of 45m^2

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Question 992424: Find the perimeter of the rectangle with length of 3x, width of 2x-1 and area of 45m^2
Answer by Timnewman(323)   (Show Source): You can put this solution on YOUR website!
Hi dear,
If lenght L=3x----(1)
and width w=2x-1--(2)
Annd,
L*w=45----(3)
Put equ 1 and 2 in 3
3x(2x-1)=45
6x²-3x-45=0
Solve the quadratic equation as follows
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=1089 is greater than zero. That means that there are two solutions: .




Quadratic expression can be factored:

Again, the answer is: 3, -2.5. Here's your graph:

Since x=3 or -2.5
L=3(3)=9m
Or
L=3(-2.5)=-7.5m
Now,w=2(3)-1=5m
Or,
w=2(-2.5)-1=-6
Ingnore those once having the nagative sign
Then,
Perimeter p=2(L+w)
p=2(9+5)m
p=28m
The perimeter of the figure is 28meters.
HOPE THIS HELPS?
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