SOLUTION: You have a rectangle. Find the value of x if L = X + 3 and W = X Area = 28

Algebra ->  Surface-area -> SOLUTION: You have a rectangle. Find the value of x if L = X + 3 and W = X Area = 28       Log On


   



Question 34566: You have a rectangle. Find the value of x if L = X + 3 and W = X
Area = 28

Answer by MrTillman(3) About Me  (Show Source):
You can put this solution on YOUR website!
Set up your equation first. Area = L W
28 = (x+3)(x) (since you said L=x+3, and w=x)
Now you have 28 = x%5E2+%2B+3x
This means you have a quadratic to solve, so set it equal to zero, by putting all terms on one side to get
x%5E2+%2B+3x+-28+=+0
Factor this to get (x+7)(x-4) = 0
Now set both to zero to solve for x x + 7 = 0 x=-7
x - 4 = 0 x=4
Since you can't have a negative value for length, the answer for x can only be 4
Therefore your width is 4 and Length = 4 + 3 or 7
x=4