When 39 is added to the square of a number, the result is 208. What is the positive number?
Answer and explanation
Correct answer: 13
Let the number be \(x\). Then \(x^2+39=208\), so \(x^2=208-39=169=13^2\). Thus, \(x=13\) or \(-13\); since the question asks for the positive number, the correct answer is 13. Exam tip: isolate the squared term first, then take the square root and check the sign condition.
Frequently asked questions
What is the correct answer to this question?
13
Why is this the correct answer?
Let the number be \(x\). Then \(x^2+39=208\), so \(x^2=208-39=169=13^2\). Thus, \(x=13\) or \(-13\); since the question asks for the positive number, the correct answer is 13. Exam tip: isolate the squared term first, then take the square root and check the sign condition.
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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