SOLUTION: This is the problem I was given. Can anyone help explain the solution to me - please. A square picture frame contains a picture with a mat border. The border is 3 inches

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: This is the problem I was given. Can anyone help explain the solution to me - please. A square picture frame contains a picture with a mat border. The border is 3 inches       Log On


   

Question 162720: This is the problem I was given. Can anyone help explain the solution to me - please.

A square picture frame contains a picture with a mat border.
The border is 3 inches thick on the sides and 4 inches thick
on the top and bottom. If the area exposed within the mat border
is 528 square inches, what are the dimensions of the original
frame?
x^2-14x-480 = 0
Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
Let the sides of the frame be X. Then the inside dimensions on the mat are (x-6) and (x-8).
Area+=+L+%2A+W
528+=+%28x-6%29%28x-8%29
528+=+x%5E2+-14x+%2B+48
0+=+x%5E2-14x-480
0+=+%28x-30%29%28x%2B16%29
So X is either 30 or -16. I can't be negative, so it must be a 30x30 picture frame