Question

The length of a rectangular field is $5$ metres less than twice the breadth. If its area is $700$ square metres, then the perimeter (in metres) of the field is

Answer 1

Let length be $l$ and breadth be $b$, so
$l=2b-5$
Now, the area is
$lb=700\Rightarrow (2b-5)b=700\Rightarrow 2b^2-5b-700=0D=25+5600=5625\Rightarrow b=\frac{5\pm \sqrt{5625}}{4}\Rightarrow b=\frac{5\pm 75}{4}\Rightarrow b=-\frac{35}{2},20\therefore b=20(\because \text{Breath cannot be negative})\Rightarrow l=40-5=35$

Hence, the perimeter
$=2(35+20)=110\text{m}$