Answer:
10 units wide; 24 units long
Step-by-step explanation:
The width is represented by the variable w in the given equation ...
w(2w +4) = 240
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This is conveniently divided by 2. Writing in standard form lets us see potential factoring.
w(w +2) = 120
w² +2w -120 = 0
(w +12)(w -10) = 0 . . . . . . factor
w = -12 or w = 10 . . . . . width
2w+4 = 2(10) +4 = 24 . . . length
The positive solution to this equation is the one of interest here.
The width of the rectangle is 10 units; its length is 24 units.
