This statement is a classic 'True or False' question found in the very first exercise of the Class 9 NCERT Mathematics textbook (Number Systems). To answer it, we must understand the family tree of numbers.
The combination of all Rational numbers and all Irrational numbers put together forms the collection of Real numbers.
The opposite statement—'Every real number is an irrational number'—is False, because a real number could also be a rational number like 4.
Statement: Every irrational number is a real number. Answer: True.
A Real Number is defined as any number that has a specific, unique point on the number line. Even though irrational numbers like $\sqrt{2}$ (1.4142...) go on forever, we can geometrically plot their exact location on a number line using the Pythagoras theorem. Since it exists on the line, it is a real number.
If a number is NOT a real number, it is an 'Imaginary' or 'Complex' number. This happens when you try to find the square root of a negative number (like $\sqrt{-5}$), which cannot exist on a standard number line.
sin 37°, cos 53°, sin 53° Values in Fraction
Learn the exact values of sin 37°, cos 37°, sin 53°, and cos 53° in fraction form. These are essential trigonometric values for CBSE Class 10 exams.
What is the formula for sin(3x)?
Learn the sin3x formula in trigonometry. Understand the expansion sin(3x) = 3sinx - 4sin³x and see a quick outline of its derivation.
Skew Symmetric Matrix
A skew symmetric matrix satisfies Aᵀ = −A. All diagonal elements = 0. Properties, examples, and how to express any square matrix as sum of symmetric and skew symmetric.
How to Find the Slant Height of a Cone
Learn the formula for the slant height of a cone (l = √(r² + h²)). Understand how Pythagoras theorem is used to calculate it in Mensuration.
Smallest 4 Digit Number — Value, Digits and Explanation
The smallest 4 digit number is 1000. It comes after 999 (the largest 3-digit number). Explanation with place value, predecessor, and number facts.
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