Advanced MathHardRectangle sides from area and a difference
Advanced Math practice question
A rectangle's length is 5 metres more than its width, and its area is 150 square metres. What is its perimeter, in metres?
Answer: 50
w(w + 5) = 150 gives w² + 5w − 150 = (w + 15)(w − 10) = 0, so w = 10 and the length is 15. Perimeter: 2(10 + 15) = 50.
Common wrong answers
- If you answered 10
- 10 is the width alone.
- If you answered 15
- 15 is the length alone.
- If you answered 25
- 25 is width + length, half the perimeter.
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