A rectangular garden must have area 49 m². What is the least perimeter, in m, it can have?

Explanation

1. 01

   With sides $x$ and $\frac{49}{x}$, $P = 2\left(x + \frac{49}{x}\right)$ and $P' = 2\left(1 - \frac{49}{x^{2}}\right) = 0$ at $x = 7$.

2. 02

   The garden is a 7 m square, with perimeter 28 m.