Multiply Square Roots: Calculate √2 × √3

Square Root Multiplication with Radicand Combination

Solve the following exercise:

23= \sqrt{2}\cdot\sqrt{3}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve the following problem
00:03 The square root of a number (A) multiplied by the square root of another number (B)
00:07 equals the square root of their product (A times B)
00:11 Apply this formula to our exercise and proceed to calculate the product
00:14 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the following exercise:

23= \sqrt{2}\cdot\sqrt{3}=

2

Step-by-step solution

In order to simplify the given expression, apply two laws of exponents:

a. The definition of root as an exponent:

an=a1n \sqrt[n]{a}=a^{\frac{1}{n}}

b. The law of exponents for exponents applied to terms in parentheses (in reverse):

xnyn=(xy)n x^n\cdot y^n =(x\cdot y)^n

Let's start by converting the square roots to exponents using the law of exponents mentioned in a':

23=212312= \sqrt{2}\cdot\sqrt{3}= \\ \downarrow\\ 2^{\frac{1}{2}}\cdot3^{\frac{1}{2}}=

Due to the fact that there is multiplication between two terms with identical exponents, we can apply the law of exponents mentioned in b' and then proceed to combine them together inside of parentheses, which are raised to the same exponent:

212312=(23)12=612=6 2^{\frac{1}{2}}\cdot3^{\frac{1}{2}}= \\ (2\cdot3)^{\frac{1}{2}}=\\ 6^{\frac{1}{2}}=\\ \boxed{\sqrt{6}}

In the final steps, we performed the multiplication within the parentheses and again used the definition of root as an exponent mentioned earlier in a' (in reverse) to return to root notation.

Therefore, the correct answer is answer b.

3

Final Answer

6 \sqrt{6}

Key Points to Remember

Essential concepts to master this topic
  • Rule: When multiplying square roots, multiply the radicands inside
  • Technique: ab=ab \sqrt{a} \cdot \sqrt{b} = \sqrt{a \cdot b} becomes 23=6 \sqrt{2} \cdot \sqrt{3} = \sqrt{6}
  • Check: Verify 62.449 \sqrt{6} \approx 2.449 and 231.414×1.732=2.449 \sqrt{2} \cdot \sqrt{3} \approx 1.414 \times 1.732 = 2.449

Common Mistakes

Avoid these frequent errors
  • Adding radicands instead of multiplying them
    Don't add 2+3=5 \sqrt{2} + \sqrt{3} = \sqrt{5} ! This gives the wrong answer because square root operations don't work like regular addition. Always multiply the numbers inside: 23=2×3=6 \sqrt{2} \cdot \sqrt{3} = \sqrt{2 \times 3} = \sqrt{6} .

Practice Quiz

Test your knowledge with interactive questions

Solve the following exercise:

\( \sqrt{\frac{2}{4}}= \)

FAQ

Everything you need to know about this question

Why can I multiply the numbers inside the square roots?

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This works because of the multiplication property of square roots: ab=ab \sqrt{a} \cdot \sqrt{b} = \sqrt{a \cdot b} . Think of it like combining what's under the radical signs!

Can I simplify √6 further?

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No, 6 \sqrt{6} is already in simplest form because 6 has no perfect square factors other than 1. Since 6 = 2 × 3 and neither 2 nor 3 are perfect squares, we can't simplify further.

What if I got 6 as my answer instead of √6?

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That's a common mistake! Remember: 23=6 \sqrt{2} \cdot \sqrt{3} = \sqrt{6} , not 6. The answer stays under the square root unless you can simplify it to a whole number.

How do I know when to use this multiplication rule?

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Use this rule whenever you're multiplying square roots together. The key phrase is "multiply" - if you see ab \sqrt{a} \cdot \sqrt{b} , combine them into ab \sqrt{a \cdot b} .

Does this work for other roots too?

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Yes! The same rule works for cube roots, fourth roots, etc. For example: 2343=83=2 \sqrt[3]{2} \cdot \sqrt[3]{4} = \sqrt[3]{8} = 2 . Just make sure the root indices are the same!

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