Answer:
length of golden rectangle = 1.618
Step-by-step explanation:
It is given that the length (L) of golden rectangle is x
And width (W) of rectangle is x-1
so we have
L = x
W= x-1
Now we have area of rectangle given by
Area = L × W
Area = x(x-1) ( we plug L= x and W= x-1)
It is given that area of rectangle is 1 square unit.
So we have

( distribute x and remove parenthesis )
( subtract 1 from both sides )
Now to solve for x we need to use the quadratic formula
For quadratic equation 
The quadratic formula is given by 
Here we have a= 1 , b=-1 c=-1 , so we have

or 
or x=-0.618
We can not have length negative
hence
length of golden rectangle = 1.618