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Understanding Square Roots & Radicals

From basic roots to radical simplification

The square root is one of the most fundamental operations in mathematics. From the Pythagorean theorem to complex engineering calculations, understanding roots is essential. This guide covers square roots, cube roots, nth roots, and how to simplify radical expressions.

What is a Square Root?

The square root of a number x is a value that, when multiplied by itself, equals x. We write it as √x or x^(1/2).

√9 = 3

because 3 × 3 = 9

∛27 = 3

because 3 × 3 × 3 = 27

⁴√16 = 2

because 2⁴ = 16

Common Square Roots

NumberPerfect?NumberPerfect?
11497
21.414...648
42819
9310010
16412111
25514412
36616913

Simplifying Radicals

To simplify a radical, factor out the largest perfect square:

√72 = √(36 × 2) = √36 × √2 = 6√2
√50 = √(25 × 2) = √25 × √2 = 5√2
√200 = √(100 × 2) = √100 × √2 = 10√2
√48 = √(16 × 3) = √16 × √3 = 4√3

Real-World Applications

Pythagorean Theorem

c = √(a² + b²)

Find the diagonal of a rectangle or hypotenuse of a right triangle

Distance Formula

d = √((x₂-x₁)² + (y₂-y₁)²)

Calculate distance between two points

Standard Deviation

σ = √(variance)

Measure spread in statistics

Quadratic Formula

x = (-b ± √(b²-4ac)) / 2a

Solve quadratic equations

Frequently Asked Questions

What is a square root?

A square root of a number x is a value that, when multiplied by itself, gives x. For example, √9 = 3 because 3 × 3 = 9. The symbol √ is called the radical sign. Every positive number has two square roots: one positive (principal root) and one negative. We usually refer to the positive root.

What is the difference between square root and cube root?

A square root (√) is a number that when multiplied by itself gives the original number (2 factors). A cube root (∛) is a number that when multiplied by itself three times gives the original number (3 factors). For example: √16 = 4 (because 4×4=16), but ∛64 = 4 (because 4×4×4=64).

What is an nth root?

An nth root is a generalization of square and cube roots. The nth root of x (written as ⁿ√x) is a number that, when raised to the power n, equals x. Mathematically, ⁿ√x = x^(1/n). For example, the 4th root of 16 is 2 because 2⁴ = 16.

What is a perfect square?

A perfect square is an integer that is the square of another integer. Examples: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144... These are perfect squares because √1=1, √4=2, √9=3, etc. Our calculator automatically detects and highlights perfect squares.

How do I simplify a radical?

To simplify a radical, factor out perfect squares. For example: √72 = √(36 × 2) = √36 × √2 = 6√2. Our calculator automatically shows simplified forms when possible, extracting the largest perfect square factor.

Can you find the square root of a negative number?

In real numbers, the square root of a negative number is undefined because no real number multiplied by itself gives a negative result. However, in complex numbers, √(-1) = i (imaginary unit). Our calculator works with real numbers and shows 'Undefined' for √negative numbers.

What is the square root of 2?

√2 ≈ 1.41421356... It's an irrational number, meaning it cannot be expressed as a fraction and its decimal expansion goes on forever without repeating. It's also known as Pythagoras' constant and appears frequently in geometry, especially in right triangles.

How accurate is this calculator?

This calculator uses JavaScript's IEEE 754 double-precision floating-point arithmetic, providing about 15-17 significant decimal digits of precision. You can adjust the display precision from 0 to 12 decimal places using the slider.

What is the relationship between roots and exponents?

Roots are the inverse of exponents. The nth root of x equals x raised to the power of 1/n. So: √x = x^(1/2), ∛x = x^(1/3), ⁴√x = x^(1/4), and so on. This relationship is fundamental in algebra and calculus.

What is batch mode?

Batch mode allows you to calculate roots for multiple numbers at once. Enter each number on a new line (or upload a file), and the calculator will show √, ∛, and nth root for all of them in a table. Results can be exported as CSV.

What numbers are shown in the Reference Table?

The Reference Table shows 30+ commonly used numbers from 1 to 1000, including all perfect squares up to 400, perfect cubes, and useful values like 2, 3, 5, 10, 100. Each entry shows √, ∛, squared, cubed, and whether it's a perfect square.

Why is √2 important?

√2 is the diagonal of a unit square (a square with side length 1). It was one of the first numbers proven to be irrational by the ancient Greeks. It appears in the Pythagorean theorem, 45-45-90 triangles, and many engineering calculations.

How do I calculate cube roots of negative numbers?

Unlike square roots, cube roots of negative numbers are defined in real numbers. For example, ∛(-8) = -2 because (-2) × (-2) × (-2) = -8. Our calculator correctly handles negative numbers for cube roots and odd nth roots.

What is the golden ratio related to square roots?

The golden ratio φ ≈ 1.618 is calculated as (1 + √5) / 2. It appears in art, architecture, nature (spiral shells, flower petals), and has unique mathematical properties like φ² = φ + 1.

Can I export my calculations?

Yes! Click 'Export as CSV' to download your results. Single mode exports the current number's roots and properties. Batch mode exports all processed numbers with their roots. Reference Table exports the entire lookup table.