SOLUTION: The area of a rectangular wall in the classroom is 216 square feet. Its length is 3 feet shorter than three times its width. Find the length and width of the wall of the classroo

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Question 749155: The area of a rectangular wall in the classroom is 216 square feet. Its length is 3 feet shorter than three times its width. Find the length and width of the wall of the classroom.
Answer by FrankM(1040) About Me  (Show Source):
You can put this solution on YOUR website!
L=3W-3
L*W=216
(3W-3)*W=216 (substituted the 3W-3 for L into second equation)
3W^2-3W=216 (distributed W through)
3W^2-3W-216=0 (subtract 216 from both sides)
W^2-W-72=0 (divide both sides by 3)

(W-9)(W+8)=0 (factored. Note, W cannot equal a negative number, we ignore -8)
W=9 L=(3*9)-3 = 24 (solved)