AlgebraHardRectangle from perimeter and a relation
Algebra practice question
The perimeter of a rectangle is 44 centimetres, and its length is 4 centimetres more than twice its width. What is the area of the rectangle, in square centimetres?
Answer: 96
Let the width be w; the length is 2w + 4. Perimeter: 2(w + 2w + 4) = 44, so 3w + 4 = 22, 3w = 18, w = 6. Length = 16. Area = 16 × 6 = 96.
Common wrong answers
- If you answered 6
- 6 is the width. Area = length × width = 16 × 6.
- If you answered 16
- 16 is the length. Multiply by the width, 6, for the area.
- If you answered 22
- 22 is half the perimeter, l + w, not the area.
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