When 17 is subtracted from the square of a number, the result is 127. What is the positive number?
Answer and explanation
Correct answer: 12
Let the number be \(x\). Then \(x^2-17=127\), so \(x^2=144\) and \(x=\pm 12\). Since the question asks for the positive number, the answer is 12. The values 10 and 14 are incorrect because their squares are 100 and 196, respectively. Exam tip: after taking a square root, consider both signs and then select the value required by the question.
Frequently asked questions
What is the correct answer to this question?
12
Why is this the correct answer?
Let the number be \(x\). Then \(x^2-17=127\), so \(x^2=144\) and \(x=\pm 12\). Since the question asks for the positive number, the answer is 12. The values 10 and 14 are incorrect because their squares are 100 and 196, respectively. Exam tip: after taking a square root, consider both signs and then select the value required by the question.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Quadratic Equations. Topic: Word Problems and Applications.
