Which option is an irrational number between 4 and 5 on the number line?
Answer and explanation
Correct answer: \(\sqrt{19}\)
\(\sqrt{19}\) is correct because \(4^2=16\) and \(5^2=25\), and since \(16<19<25\), we have \(4<\sqrt{19}<5\). Also 19 is not a perfect square, so \(\sqrt{19}\) is irrational. The closest distractor \(\frac{9}{2}=4.5\) lies between 4 and 5 but is rational. \(\sqrt{16}=4\) and \(\sqrt{25}=5\) are the end points, not inside the open interval (4,5). Exam tip: to check whether a square root is between two integers, compare the radicand with the squares of those integers and check if it's a perfect square.
Frequently asked questions
What is the correct answer to this question?
\(\sqrt{19}\)
Why is this the correct answer?
\(\sqrt{19}\) is correct because \(4^2=16\) and \(5^2=25\), and since \(16<19<25\), we have \(4<\sqrt{19}<5\). Also 19 is not a perfect square, so \(\sqrt{19}\) is irrational. The closest distractor \(\frac{9}{2}=4.5\) lies between 4 and 5 but is rational. \(\sqrt{16}=4\) and \(\sqrt{25}=5\) are the end points, not inside the open interval (4,5). Exam tip: to check whether a square root is between two integers, compare the radicand with the squares of those integers and check if it's a perfect square.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Polynomials. Topic: Irrational numbers and real numbers.
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