Question

A farmer has 350 feet of fence available to enclose a 6125 square foot region in the shape of adjoining squares with sides of length x and y. The big square has sides of x and the small square has sides of length y. Find x and y

Answer 1

x = 77 ft; y = 14 ft

Explanation:

We assume that "adjoining squares" means the small square shares a side with the large square, so the total length (in feet) of fence required for the enclosure is ...

4x +3y = 350

The sum of the two areas is 6125 ft², so we have another relation:

x² +y² = 6125

We can use the first equation to write an expression for y, then substitute that into the second equation. The result is a quadratic in x.

3y = 350 -4x

y = (350 -4x)/3

Then ...

x² + ((350 -4x)/3)² = 6125 . . . substitute for y

9x² +(350 -4x)² = 55125 . . . . multiply by 9

25x² -2800x +67375 = 0 . . . . subtract 55125 and simplify

x² -112x +2695 = 0

(x -35)(x -77) = 0

This has two solutions: x = 35 and x = 77. We know that the square of sides x must use more than half the fence, so it must have side lengths greater than ...

(350/2)/4 = 43.75 . . . . feet

The appropriate choice for x is 77 feet. Then ...

y = (350 -4x)/3 = 42/3 = 14 . . . feet

x and y are 77 feet and 14 feet, respectively.