When 6 is subtracted from a number and the result is multiplied by the same number, the product is 135. What is the positive number?
Answer and explanation
Correct answer: 15
Let the number be \(x\). According to the question, \(x(x-6)=135\), so \(x^2-6x-135=0\). Factoring gives \((x-15)(x+9)=0\), hence \(x=15\) or \(x=-9\). Since the question asks for the positive number, the answer is \(15\). In an exam, find both roots and then apply the stated condition, such as ‘positive’.
Frequently asked questions
What is the correct answer to this question?
15
Why is this the correct answer?
Let the number be \(x\). According to the question, \(x(x-6)=135\), so \(x^2-6x-135=0\). Factoring gives \((x-15)(x+9)=0\), hence \(x=15\) or \(x=-9\). Since the question asks for the positive number, the answer is \(15\). In an exam, find both roots and then apply the stated condition, such as ‘positive’.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Quadratic Equations. Topic: Word Problems and Applications.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
