x(x+3.7)= 18.3

Question

On my assignment I've got a question that I'm stuck with.  I've got to find dimensions of a rectangle with the

information that is given:
Area: 18.3 cm² ;

Width: x
Length: x+3.7

 

so i came up with:
x(x+3.7)=18.3
x²+3.7x-18.3=0

 

Then when I'm trying to use the quadratic equation formula - I come up with answers, which do not work for me. HELP!

Answer 1

The quadratic formula will work for this problem.

 

We have a = 1

b = 3.7

c = - 18.3

 

We compute (-3.7 + sqrt(3.7² + 4 18.3) /2   =  2.81

 

We must take the positive sign of the square root, else we get a negative length (not physical).

Note also that the expression has + 4 18.3  because c is negative.

 

To check, we note that 2.81 (2.81 + 3.7) does equal 18.3