A garden has \(x\) rows, with \(x-4\) plants in each row. If there are 525 plants in total, how many rows are there?
Answer and explanation
Correct answer: 25
The total number of plants gives \(x(x-4)=525\), or \(x^2-4x-525=0\). Factoring, \((x-25)(x+21)=0\), so \(x=25\) or \(x=-21\). Since the number of rows cannot be negative, \(x=25\) is the valid answer. In such word problems, always reject a negative value for a physical quantity.
Frequently asked questions
What is the correct answer to this question?
25
Why is this the correct answer?
The total number of plants gives \(x(x-4)=525\), or \(x^2-4x-525=0\). Factoring, \((x-25)(x+21)=0\), so \(x=25\) or \(x=-21\). Since the number of rows cannot be negative, \(x=25\) is the valid answer. In such word problems, always reject a negative value for a physical quantity.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Quadratic Equations. Topic: Word Problems and Applications.
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