MHB Word problem - linear equation.

[paulmdrdo1]

please help me with this problem

please use single variable only.

The length of a rectangular swimming pool is twice its width. The pool is surrounded by a cement walk 4ft wide. If the area of the walk is 748 ft^2, determine the dimensions of the pool.

let x = width of the pool
2x = length of the pool

the dimensions of the pool and cement walk combined

x+8 = width
2x+8 = length

the area of the pool plus the area of the cement walk is equal to the whole area.

$(2x+8)(x+8)=748+2x^2$

$x= 28.5$

the dimensions of the pool is 28.5 ft by 57 ft.

but the answer in my book is 30 ft. by 60 ft. why is that? where did I miss?

regards!

please use one variable only.

 

[MarkFL]

The area of the walk (using your variables) is:

$$2(4x+4(2x+8))=748$$

$$4(6x+16)=748$$

$$6x+16=187$$

$$6x=171$$

$$x=28.5$$

I agree with you.

 

[Opalg]

If the answer is 30 ft x 60 ft then the area of the walk would be 784, not 748. Did you read the question correctly?