Question 750920
x(x+1) = 90


x^2+x = 90


x^2+x-90 = 0


(x+10)(x-9) = 0


x+10=0 or x-9=0


x=-10 or x = 9


Ignore the negative solution. 


The only solution that makes sense is x = 9, so x+1 = 10 


The length is 10 ft.