Advanced MathHardQuadratic from a rectangle's area
Advanced Math practice question
A rectangular garden has an area of 60 square metres, and its length is 7 metres more than its width. What is the width of the garden, in metres?
Answer: 5
Let the width be w; the length is w + 7. Area: w(w + 7) = 60, so w² + 7w − 60 = 0, which factors as (w + 12)(w − 5) = 0. The width can't be −12, so w = 5. Check: 5 × 12 = 60.
Common wrong answers
- If you answered 6
- 6 × 13 = 78, not 60. The width that works is 5.
- If you answered 12
- 12 is the LENGTH (5 + 7). The question asks for the width.
- If you answered -12
- −12 does solve the equation, but a width can't be negative.
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