The breadth of a prayer hall is $x$ m and its length is $(2x+1)$ m. If its area is $300\text{ m}^2$, what are its dimensions? 

The equation is $x(2x+1)=300$, i.e. $2x^2+x-300=0$. Factorising: $2x^2-24x+25x-300=0$, so $(x-12)(2x+25)=0$. This gives $x=12$ or $x=-12.5$. Since breadth cannot be negative, breadth $=12$ m and length $=2(12)+1=25$ m.