SOLUTION: Please help solve. If the sides of a square are lengthened by 7cm, the area becomes 121 cm^2. Find the length of a side of the original square. The length of a side of the ori

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Please help solve. If the sides of a square are lengthened by 7cm, the area becomes 121 cm^2. Find the length of a side of the original square. The length of a side of the ori      Log On


   

Question 150433: Please help solve.
If the sides of a square are lengthened by 7cm, the area becomes 121 cm^2. Find the length of a side of the original square. The length of a side of the original square is ___________cm.
Answer by jojo14344(1513) About Me  (Show Source):
You can put this solution on YOUR website!
Let's make "x" = side of the orginal square.
Since the Area is given when the sides are lengthened by 7cm, we'll use this condition in solving for "x". So the sides will be x%2B7, and going to our formula for Area of square,
A=%28sides%29%5E2
A=%28x%2B7%29%5E2 ---------> 121cm%5E2=x%5E2%2B14x%2B49
x%5E2%2B14x-72=0 ------> %28x%2B18%29%28x-4%29=0
2 values,
x=-18, don't use since "negative"
x=4cm, USE THIS DISABLED_event_ONE= ORIGINAL LENGTH
It just makes sense to have this length. Why?
Simply, A=%28new+sides%29%5E2
121cm%5E2=+%284%2B7%29%5E2
121cm%5E2=121cm%5E2
Thank you,
Jojo