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Multiplying Negative Radicals Calculator

Reviewed by Calculator Editorial Team

Multiplying negative radicals can be tricky because of the rules of exponents and roots. This calculator helps you multiply negative square roots and cube roots correctly by following mathematical conventions.

How to Multiply Negative Radicals

When multiplying negative radicals, you need to follow these key rules:

  1. Multiply the radicands (the numbers inside the radicals) together
  2. Multiply the coefficients (the numbers outside the radicals) together
  3. Apply the rules for negative numbers in radicals

The result will be a product of the coefficients and the square root (or cube root) of the product of the radicands.

Key Formula

For two negative radicals: -√a × -√b = √(a × b)

For cube roots: -∛a × -∛b = ∛(a × b)

Formula for Multiplying Negative Radicals

The general formula for multiplying negative radicals is:

For square roots: (-√a) × (-√b) = √(a × b)

For cube roots: (-∛a) × (-∛b) = ∛(a × b)

This formula works because multiplying two negative numbers gives a positive result, and the square root (or cube root) of a product is the product of the square roots (or cube roots).

Examples of Multiplying Negative Radicals

Square Root Example

Multiply -√8 and -√2:

-√8 × -√2 = √(8 × 2) = √16 = 4

Cube Root Example

Multiply -∛27 and -∛3:

-∛27 × -∛3 = ∛(27 × 3) = ∛81 = 3∛3

Common Mistakes

When working with negative radicals, these common errors occur:

  1. Forgetting that the product of two negatives is positive
  2. Incorrectly multiplying the radicands before applying the square root
  3. Miscounting the exponents when simplifying results

Remember: The negative signs cancel out when multiplying two negative radicals.

FAQ

Can I multiply negative radicals with different indices?

Yes, you can multiply negative square roots with negative cube roots, but the result will be a mixed radical expression that may need further simplification.

What happens when I multiply a negative radical by a positive radical?

The result will be a negative radical. For example, -√8 × √2 = -√16 = -4.

How do I simplify the result of multiplying negative radicals?

Simplify the radicand by factoring it into perfect squares (or cubes) and then taking the square root (or cube root) of the simplified expression.