Root Calculator
Calculate square roots, cube roots, and any nth root of a number, or simplify a square-root radical expression into its simplest exact form.
Frequently Asked Questions
What is a square root and how is it calculated?
The square root of x (written √x or x^(1/2)) is the number r such that r² = x. Perfect squares have exact integer roots: √1=1, √4=2, √9=3, √16=4, √25=5, √36=6, √49=7, √64=8, √81=9, √100=10, √121=11, √144=12. Non-perfect squares produce irrational numbers: √2 ≈ 1.4142, √3 ≈ 1.7321, √5 ≈ 2.2361. In geometry, the Pythagorean theorem (c = √(a² + b²)) makes square roots essential for calculating distances and hypotenuses.
What is the cube root and when is it used?
The cube root of x (∛x or x^(1/3)) is the number r such that r³ = x. Unlike square roots, cube roots of negative numbers are real: ∛(−8) = −2 because (−2)³ = −8. Perfect cubes: ∛1=1, ∛8=2, ∛27=3, ∛64=4, ∛125=5, ∛216=6, ∛1000=10. Real-world uses: finding the side length of a cube given its volume (side = ∛Volume), calculating the radius of a sphere from its volume (r = ∛(3V÷4π)), and scaling in 3D design and physics.
Can you take the square root of a negative number?
Not in the real number system — squaring any real number always produces a non-negative result, so no real number r satisfies r² = −1. To extend mathematics to include these roots, the imaginary unit i is defined as i = √(−1). Complex numbers (a + bi) then allow operations like √(−9) = 3i. Complex numbers are not just mathematical curiosities — they are essential in electrical engineering (AC circuit analysis using impedance), quantum mechanics, signal processing, and the mathematics of rotations.
How do you simplify a radical expression like √72?
Factor out perfect squares from under the radical. √72 = √(36 × 2) = √36 × √2 = 6√2. Method: find the prime factorization (72 = 2³ × 3²), then group pairs: 2³ = 2² × 2 and 3² = 3². Each pair comes outside: √(2² × 3² × 2) = 2 × 3 × √2 = 6√2. More examples: √50 = 5√2; √75 = 5√3; √180 = 6√5; √200 = 10√2. Simplified radical form is exact (no rounding), making it preferred in algebra and geometry.
What is the nth root and how do roots relate to fractional exponents?
The nth root of x is written ⁿ√x or x^(1/n): the number r such that rⁿ = x. Fractional exponents unify roots and powers: x^(m/n) = (ⁿ√x)^m. Examples: 8^(2/3) = (∛8)² = 2² = 4; 16^(3/4) = (⁴√16)³ = 2³ = 8; 32^(0.4) = 32^(2/5) = (⁵√32)² = 2² = 4. This notation is used in compound interest (growth rate = future/present)^(1/n) − 1), statistics (standard deviation = √variance), and physics (inverse-square laws).