A garden contains 850 plants. If there are x rows and each row has \(x-9\) plants, how many rows are there?
Answer and explanation
Correct answer: 34
The total number of plants gives the equation \(x(x-9)=850\). Thus, \(x^2-9x-850=0\), which factors as \((x-34)(x+25)=0\). Therefore, \(x=34\) or \(x=-25\). Since the number of rows cannot be negative, the valid answer is 34. Check: \(34\times(34-9)=34\times25=850\). Exam tip: Substitute the answer back into the original situation and reject any negative value that is not meaningful in context.
Frequently asked questions
What is the correct answer to this question?
34
Why is this the correct answer?
The total number of plants gives the equation \(x(x-9)=850\). Thus, \(x^2-9x-850=0\), which factors as \((x-34)(x+25)=0\). Therefore, \(x=34\) or \(x=-25\). Since the number of rows cannot be negative, the valid answer is 34. Check: \(34\times(34-9)=34\times25=850\). Exam tip: Substitute the answer back into the original situation and reject any negative value that is not meaningful in context.
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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