What is the perimeter of the rectangle?

Question

For a particular rectangle, three times the width is 10 meters longer than the length. The area of the rectangle is 312 square meters. What is the perimeter of the rectangle?

Answer 1

let x =length of the rectangle

then width can equal y and 3y = x + 10, so x = 3y -10.

 

The area:  xy = 312

(3y-10)y = 312

Now the calculation of perimeter is straightforward, left to you.

 

3y² - 10y -312 = 0

 

the only positive solution to this quadratic is y=12, so x=26.