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

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\( 5^4\times25= \)

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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