SOLUTION: This is from Activity Bank, INTEGRATED MATHEMATICS 1 Copyright by Houghton Mifflin Company. The city of Casablanca, Morocco has the world's largest swimming pool. The distance

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: This is from Activity Bank, INTEGRATED MATHEMATICS 1 Copyright by Houghton Mifflin Company. The city of Casablanca, Morocco has the world's largest swimming pool. The distance       Log On


   



Question 196132: This is from Activity Bank, INTEGRATED MATHEMATICS 1 Copyright by Houghton Mifflin Company.
The city of Casablanca, Morocco has the world's largest swimming pool. The distance between two opposite corners of the pool is about 1590 ft. The length is about 1325 ft. longer than the width. What are the length and width of the pool?

Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
The distance between two opposite corners of the pool is about 1590 ft. The length is about 1325 ft. longer than the width. What are the length and width of the pool?
.
Because the pool is rectangular you can apply Pythagorean theorem:
.
Let w = width
then
w+1325 = length
.
w^2 + (w+1325)^2 = 1590^2
w^2 + (w+1325)(w+1325) = 1590^2
w^2 + (w^2+2650w+1755625) = 2528100
2w^2 + 2650w + 1755625 = 2528100
2w^2 + 2650w - 772475 = 0
Solving using the quadratic equation yields:
w = {245.87, -1570.87}
We can throw out the negative solution leaving:
w = 245.87 feet (width)
.
length:
w+1325 = 245.87+1325 = 1570.87 feet (length)
.
Details of quadratic follows:
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation aw%5E2%2Bbw%2Bc=0 (in our case 2w%5E2%2B2650w%2B-772475+=+0) has the following solutons:

w%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%282650%29%5E2-4%2A2%2A-772475=13202300.

Discriminant d=13202300 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-2650%2B-sqrt%28+13202300+%29%29%2F2%5Ca.

w%5B1%5D+=+%28-%282650%29%2Bsqrt%28+13202300+%29%29%2F2%5C2+=+245.874234553138
w%5B2%5D+=+%28-%282650%29-sqrt%28+13202300+%29%29%2F2%5C2+=+-1570.87423455314

Quadratic expression 2w%5E2%2B2650w%2B-772475 can be factored:
2w%5E2%2B2650w%2B-772475+=+2%28w-245.874234553138%29%2A%28w--1570.87423455314%29
Again, the answer is: 245.874234553138, -1570.87423455314. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+2%2Ax%5E2%2B2650%2Ax%2B-772475+%29