21.7k views
0 votes
During the holiday, students went swimming in a local rectangular pool. The pool measures 20 feet by 35 feet. It is surrounded by a patio that is uniform width. Find the width of the patio if the total area of the pool and patio is 1350 sqr feet. Write a quadratic equation to solve the problem.

User Maglob
by
3.8k points

1 Answer

1 vote

Answer:

The width of the patio is 3/2 feet.

Explanation:

following equation to solve for w:

(20+2w) * (35+2w) = 1350

Expanding the equation, we get:

700 + 140w + 70w^2 = 1350

Subtracting 700 from both sides, we get:

140w + 70w^2 = 650

Dividing both sides by 10, we get:

14w + 7w^2 = 65

We can now solve for w using the quadratic formula:

w = (-b +/- sqrt(b^2-4ac)) / 2a

where a = 7, b = 14, and c = -65. Substituting these values into the formula, we get:

w = (-14 +/- sqrt(14^2-47(-65))) / 2*7

w = (-14 +/- sqrt(196+1820)) / 14

w = (-14 +/- sqrt(2016)) / 14

w = (-14 +/- 44) / 14

To find the width of the patio, we need to find the area of the pool and the area of the patio. Let's call the width of the patio "w". The area of the pool is 20 * 35 = <<20*35=700>>700 square feet. The area of the patio is (20+2w) * (35+2w) = 1350 sqr feet. We can set up the following equation to solve for w:

(20+2w) * (35+2w) = 1350

Expanding the equation, we get:

700 + 140w + 70w^2 = 1350

Subtracting 700 from both sides, we get:

140w + 70w^2 = 650

Dividing both sides by 10, we get:

14w + 7w^2 = 65

We can now solve for w using the quadratic formula:

w = (-b +/- sqrt(b^2-4ac)) / 2a

where a = 7, b = 14, and c = -65. Substituting these values into the formula, we get:

w = (-14 +/- sqrt(14^2-47(-65))) / 2*7

w = (-14 +/- sqrt(196+1820)) / 14

w = (-14 +/- sqrt(2016)) / 14

w = (-14 +/- 44) / 14

This means that the width of the patio is either 3/2 or -5/2 feet. Since the width cannot be negative, the width of the patio must be 3/2 feet.

The quadratic equation we can use to solve this problem is:

w^2 + 14w - 65 = 0

User Matt McHugh
by
3.7k points