Radical Simplifier — Simplify Square Roots & nth Roots (Free)
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A radical simplifier rewrites a root so no perfect power is left inside. To simplify √72, find the largest perfect square factor, 36, and split the root: √72 = √36 · √2 = 6√2 ≈ 8.4853. Cube and higher roots work the same way with perfect cubes or nth powers: ∛54 = ∛27 · ∛2 = 3∛2.
√72 in simplest radical form is 6√2, which is about 8.4853.
2 comes out
3 comes out
stays inside
Show steps
- The index is 2, so you are looking for perfect squares: factors that appear in groups of 2. Each group of 2 equal factors can leave the root as a single factor.
- Write 72 as a product of primes: 72 = 2³ · 3².
- Group the primes in sets of 2: 2³ gives one group, so 2 comes out and 2 stays inside; 3² gives one group, so 3 comes out.
- So the largest perfect square factor is 36 = 6², and 72 = 36 × 2. Then √72 = √36 · √2 = 6√2.
- Answer: √72 = 6√2.
- Check with decimals: √72 ≈ 8.4853 and 6√2 ≈ 8.4853. They match.
Simplest radical form means: no perfect square factor left under the root, no fraction under the root, and no radical in a denominator.
How to use the radical simplifier
- Pick a tab: Simplify a radical, Add & subtract, Multiply or Divide & rationalize.
- To simplify one root, enter an optional coefficient, choose the index (2 for square roots, 3 for cube roots, up to 10) and type the radicand. It can be a whole number, a fraction, a decimal or a term with variables such as 18x^4y^3.
- In the other tabs, type radicals with √, ∛, ∜ or the symbol buttons. You can also write sqrt(50), cbrt(16) or root(5, 32).
- Read the simplest radical form, the decimal value and the grouping picture, then open Show steps for the full working.
How to simplify a radical
The rule behind every step is the product rule for radicals: ⁿ√(ab) = ⁿ√a · ⁿ√b, for a and b that are not negative. You split the radicand into a perfect power times whatever is left, then take the root of the perfect power.
- Write the radicand as a product of primes. For 72, that is 2³ · 3².
- Circle groups of equal factors, with as many in each group as the index: pairs for square roots, triples for cube roots.
- Each full group leaves the root as one factor. Leftover factors stay inside.
- Multiply what came out by any coefficient already in front.
For √72, the pairs are 2·2 and 3·3, with one 2 left over. So 2 · 3 = 6 comes out and 2 stays in: √72 = 6√2. For ∜162 = ∜(2 · 3⁴), the four 3s form one group, so ∜162 = 3∜2.
Radicals with variables
Divide each exponent by the index. The quotient is the power that comes out, and the remainder stays inside. For √(18x⁴y³): 18 = 9 · 2, x⁴ gives 4 ÷ 2 = 2 remainder 0, and y³ gives 3 ÷ 2 = 1 remainder 1. So √(18x⁴y³) = 3x²y√(2y). The calculator assumes the variables are positive, which is the usual convention in algebra classes, so no absolute value signs are needed.
Reducing the index
If every exponent inside shares a factor with the index, you can divide both by it. ⁶√8 = ⁶√(2³) = 2^(3/6) = 2^(1/2), which is √2. Many tools stop at ⁶√8; the calculator reduces it for you.
Perfect squares, cubes and worked examples
Knowing the first few perfect powers makes the search quick. Perfect squares: 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144. Perfect cubes: 8, 27, 64, 125, 216, 343, 512, 729, 1000.
| Radical | Split | Simplest form | Decimal |
|---|---|---|---|
| √50 | √25 · √2 | 5√2 | 7.0711 |
| √48 | √16 · √3 | 4√3 | 6.9282 |
| √75 | √25 · √3 | 5√3 | 8.6603 |
| √98 | √49 · √2 | 7√2 | 9.8995 |
| √200 | √100 · √2 | 10√2 | 14.1421 |
| 3√20 | 3 · √4 · √5 | 6√5 | 13.4164 |
| ∛16 | ∛8 · ∛2 | 2∛2 | 2.5198 |
| ∛250 | ∛125 · ∛2 | 5∛2 | 6.2996 |
| ∜48 | ∜16 · ∜3 | 2∜3 | 2.6321 |
Adding and subtracting radicals
Only like radicals combine: same index and same radicand. Treat them like like terms in algebra. Always simplify first, because radicals that look different often match after simplifying.
Example: 3√12 + 5√27 − √48. Simplify each one: √12 = 2√3, √27 = 3√3 and √48 = 4√3. The expression becomes 6√3 + 15√3 − 4√3 = (6 + 15 − 4)√3 = 17√3 ≈ 29.4449.
Multiplying radicals
With the same index, multiply the outside numbers together and the radicands together, then simplify: 2√6 · 3√15 = 6√90 = 6 · 3√10 = 18√10. For binomials, distribute (FOIL) and combine like terms. Conjugates such as (2 + √3)(2 − √3) give a whole number, because (a + b)(a − b) = a² − b² = 4 − 3 = 1.
Different indexes need a common index first: √2 · ∛2 = ⁶√(2³) · ⁶√(2²) = ⁶√32 ≈ 1.7818.
Dividing radicals and rationalizing the denominator
Simplest radical form has no root in a denominator. To clear one:
- One square root: multiply top and bottom by that root. 3/√2 = 3√2/(√2 · √2) = 3√2/2.
- A cube or higher root: multiply by whatever makes the radicand a perfect power. 5/∛4: since 4 · 2 = 8 = 2³, multiply by ∛2 to get 5∛2/2.
- Two terms: multiply by the conjugate. 6/(3 − √5) = 6(3 + √5)/(9 − 5) = (18 + 6√5)/4 = (9 + 3√5)/2 ≈ 7.8541.
Common mistakes when simplifying radicals
| Mistake | Why it is wrong | Correct |
|---|---|---|
| √72 = 2√18 | Not finished: 18 still contains 9 | 6√2 |
| √(9 + 16) = 3 + 4 | A root of a sum does not split | √25 = 5 |
| √2 + √3 = √5 | Unlike radicals do not combine | √2 + √3 stays as it is |
| 3√20 = 2√5 | The 3 in front was dropped | 3 · 2√5 = 6√5 |
| √(−4) = −2 | Even roots of negatives are not real | 2i (not a real number) |
Where simplified radicals show up
Exact radicals appear in the Pythagorean theorem (a square with side 1 has diagonal √2), in special right triangles (30-60-90 sides 1, √3, 2), in the quadratic formula, in distance and midpoint problems, and in geometry answers that tests expect in exact form rather than as rounded decimals.
Simplifying radicals practice quiz: 10 questions
Test yourself with 10 multiple-choice questions. Choose an answer and press Submit to see if you are right and why. Your score appears at the end.
48 = 16 × 3 and 16 is the largest perfect square factor, so √48 = 4√3. 2√12 is not finished because 12 still contains 4.
32 = 16 × 2 gives 4√2, and x⁵ = x⁴ · x gives x²√x. Together: 4x²√(2x).
√8 = 2√2 and √50 = 5√2. These are like radicals, so add the coefficients: 7√2. Radicands are never added, so √58 is wrong.
Multiply by the conjugate 1 − √3: 2(1 − √3)/(1 − 3) = 2(1 − √3)/(−2) = √3 − 1.
Conjugates multiply to a difference of squares: 3² − (√2)² = 9 − 2 = 7.
30 = 2 × 3 × 5 has no perfect square factor. √45 = 3√5, ∛16 = 2∛2 and √(1/3) has a fraction under the root.
Quiz complete
Frequently asked questions
What is simplified radical form?
A radical is in simplest form when no perfect power factor is left under the root, there is no fraction under the root, and no radical is left in a denominator. The index should also be as small as possible, so ⁶√8 becomes √2.
What is radical 12 simplified?
√12 = √4 · √3 = 2√3, about 3.4641. Check it by squaring: (2√3)² = 4 · 3 = 12.
What is radical 32 simplified?
√32 = √16 · √2 = 4√2, about 5.6569. Stopping at 2√8 is a common slip, because 8 still contains the perfect square 4.
How do you simplify radical expressions with variables?
Simplify the number and each variable separately. Divide each exponent by the index: the quotient comes out and the remainder stays in. For example, √(45x⁵) = 3x²√(5x).
How do you simplify radical fractions?
Take the root of the top and bottom separately, then rationalize. √(5/9) = √5/3. If the denominator is not a perfect square, multiply inside first: √(5/8) = √(10/16) = √10/4.
Can a TI-84 simplify radicals?
Standard TI-84 models show a decimal (√72 gives about 8.485), not the exact form 6√2. Use the calculator above for the exact answer and steps, and the decimal to check it.
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