Multiply Cube Roots: Solving ∛(2²) × ∛2 Step by Step

Cube Root Operations with Fractional Exponents

Solve the following exercise:

22323= \sqrt[3]{2^2}\cdot\sqrt[3]{2}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Simplify the following expression
00:03 The C root of the value A to the power of B
00:06 The result will equal number A to the power of B divided by C
00:09 Every number is essentially to the power of 1
00:12 We will use this formula in our exercise
00:15 When multiplying powers with equal bases
00:20 The power of the result equals the sum of the powers
00:24 We will use this formula in our exercise, and add the powers
00:33 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:

22323= \sqrt[3]{2^2}\cdot\sqrt[3]{2}=

2

Step-by-step solution

To simplify the given expression we use two laws of exponents:

A. The law of roots (expanded):

amn=amn=(an)m \sqrt[\textcolor{blue}{n}]{a^{\textcolor{red}{m}}}=a^{\frac{\textcolor{red}{m}}{\textcolor{blue}{n}}} =(\sqrt[\textcolor{blue}{n}]{a})^{\textcolor{red}{m}}

B. The law of exponents for multiplication of terms with identical bases:

aman=am+n a^m\cdot a^n=a^{m+n}

Let's start from the root level to write exponents using the law of exponents shown in A:

22323=223213=223213= \sqrt[\textcolor{blue}{3}]{2^{\textcolor{red}{2}}}\cdot\sqrt[\textcolor{blue}{3}]{2}= \\ \sqrt[\textcolor{blue}{3}]{2^{\textcolor{red}{2}}}\cdot\sqrt[\textcolor{blue}{3}]{2^{\textcolor{red}{1}}}= \\ \downarrow\\ 2^{\frac{\textcolor{red}{2}}{\textcolor{blue}{3}}}\cdot2^{\frac{\textcolor{red}{1}}{\textcolor{blue}{3}}} =

We continue, since multiplication is performed between two terms with identical bases - we use the law of exponents shown in B:

223213=223+13= 2^{\frac{2}{3}}\cdot2^{\frac{1}{3}}= \\ 2^{\frac{2}{3}+\frac{1}{3}}=

We continue and perform (separately) the operation of combining the numerators in the exponent fraction that was obtained, this is done by expanding each of the numerators to the common denominator - the number 3, then we perform the addition and subtraction operations in the numerator of the fraction:

23+13=2+13=33=1 \frac{2}{3}+\frac{1}{3}=\\ \frac{2+1}{3}=\\ \frac{3}{3}=\\ 1

In other words - we get that:

223+13=21=2 2^{\frac{2}{3}+\frac{1}{3}}=\\ 2^{1}=\\ \boxed{2}

Let's summarize the process of simplifying the expression:

22323=223+13=2 \sqrt[3]{2^2}\cdot\sqrt[3]{2}= \\ \downarrow\\ 2^{\frac{2}{3}+\frac{1}{3}}=\\ \boxed{2}

Therefore, the correct answer is answer A.

3

Final Answer

2 2

Key Points to Remember

Essential concepts to master this topic
  • Root Rule: Convert amn=amn \sqrt[n]{a^m} = a^{\frac{m}{n}} to fractional exponents
  • Technique: Add exponents when multiplying same bases: 223213=233 2^{\frac{2}{3}} \cdot 2^{\frac{1}{3}} = 2^{\frac{3}{3}}
  • Check: Substitute back: 4323=83=2 \sqrt[3]{4} \cdot \sqrt[3]{2} = \sqrt[3]{8} = 2

Common Mistakes

Avoid these frequent errors
  • Multiplying the cube roots as regular multiplication
    Don't multiply 22323 \sqrt[3]{2^2} \cdot \sqrt[3]{2} like 222=8 2^2 \cdot 2 = 8 ! This ignores the cube root completely and gives wrong results. Always convert roots to fractional exponents first, then apply exponent rules.

Practice Quiz

Test your knowledge with interactive questions

\( (4^2)^3+(g^3)^4= \)

FAQ

Everything you need to know about this question

Why do we convert cube roots to fractional exponents?

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Converting cube roots to fractional exponents lets us use familiar exponent rules! 223=223 \sqrt[3]{2^2} = 2^{\frac{2}{3}} is much easier to work with than keeping it as a cube root.

How do I remember the exponent rule for multiplication?

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Remember: when multiplying terms with the same base, you add the exponents. So 223213=223+13 2^{\frac{2}{3}} \cdot 2^{\frac{1}{3}} = 2^{\frac{2}{3}+\frac{1}{3}} .

What if I get a fraction that doesn't simplify to a whole number?

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That's okay! Many problems result in fractional exponents. Just make sure to add the fractions correctly and simplify if possible. Not every answer will be a nice whole number.

Can I multiply what's inside the cube roots directly?

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Yes, but only sometimes! You can write 22323=2223=233=2 \sqrt[3]{2^2} \cdot \sqrt[3]{2} = \sqrt[3]{2^2 \cdot 2} = \sqrt[3]{2^3} = 2 . This works because both terms have the same index (3).

How do I check if my final answer is correct?

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Calculate each cube root separately first: 431.587 \sqrt[3]{4} \approx 1.587 and 231.260 \sqrt[3]{2} \approx 1.260 . Then multiply: 1.587 × 1.260 ≈ 2 ✓

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