What is the length of a rectangular garden whose perimeter is 32cm and area 39cm2?

What is the length of a rectangular garden whose perimeter is 32cm and area 39cm²?

Correct Answer: Option C

Explanation

perimeter = 2(l + b) = 32
l + b = (frac{32}{2})
l + b = 16
b = 16 – 1…….(1)
Area = l + b = 39
lb = 39 …..(2)
put (1) into (2)
l(16 – 1) = 39
16l – l² = 39
l² = 13l – 3l + 39 = 0
l(l – 13) – 3(1 – 13) = 0
(l – 3)(l + 130 = 0
l – 3 = 0 or l – 13 = 0
l = 3cm or l = 13cm; The length in 13cm