Solve the Square Root Product: √4 × √4 Step-by-Step

Square Root Multiplication with Identical Radicals

Solve the following exercise:

44= \sqrt{4}\cdot\sqrt{4}=

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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 root of number (A) times root of another number (B)
00:07 Equals the root of their product (A times B)
00:11 Apply this formula to our exercise and calculate the product
00:14 Calculate the root of 16
00:17 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:

44= \sqrt{4}\cdot\sqrt{4}=

2

Step-by-step solution

In order to simplify the given expression, we will use 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 power of a power:

(am)n=amn (a^m)^n=a^{m\cdot n}

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

44=412412= \sqrt{4}\cdot\sqrt{4}= \\ \downarrow\\ 4^{\frac{1}{2}}\cdot4^{\frac{1}{2}}= Let's continue, notice that we got a number multiplied by itself, therefore, according to the definition of exponents we can write the expression we got as a power of that same number, then - we'll use the law of exponents mentioned in b' and perform the exponent operation on the term in parentheses:

412412=(412)2=4122=41=4 4^{\frac{1}{2}}\cdot4^{\frac{1}{2}}= \\ (4^{\frac{1}{2}})^2=\\ 4^{\frac{1}{2}\cdot2}=\\ 4^1=\\ \boxed{4} Therefore, the correct answer is answer c.

3

Final Answer

4 4

Key Points to Remember

Essential concepts to master this topic
  • Property: Square roots can be converted to fractional exponents
  • Technique: 44=412412=(412)2 \sqrt{4} \cdot \sqrt{4} = 4^{\frac{1}{2}} \cdot 4^{\frac{1}{2}} = (4^{\frac{1}{2}})^2
  • Check: Since 4=2 \sqrt{4} = 2 , verify: 2×2=4 2 \times 2 = 4

Common Mistakes

Avoid these frequent errors
  • Adding square roots instead of multiplying
    Don't think 44=8 \sqrt{4} \cdot \sqrt{4} = \sqrt{8} ! This confuses the product rule ab=ab \sqrt{a} \cdot \sqrt{b} = \sqrt{ab} with addition. Always multiply: 44=4×4=16=4 \sqrt{4} \cdot \sqrt{4} = \sqrt{4 \times 4} = \sqrt{16} = 4 .

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 isn't the answer 8 \sqrt{8} ?

+

That would be adding square roots, not multiplying! When multiplying 44 \sqrt{4} \cdot \sqrt{4} , you get 4×4=16=4 \sqrt{4 \times 4} = \sqrt{16} = 4 .

Can I just multiply the numbers under the square roots?

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Yes! The product rule states ab=a×b \sqrt{a} \cdot \sqrt{b} = \sqrt{a \times b} . So 44=4×4=16=4 \sqrt{4} \cdot \sqrt{4} = \sqrt{4 \times 4} = \sqrt{16} = 4 .

What's the easier way to solve this?

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Since 4=2 \sqrt{4} = 2 , you can simply calculate 2×2=4 2 \times 2 = 4 . Both methods give the same answer!

Why do we use exponents in the solution?

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Converting to exponents (4=412 \sqrt{4} = 4^{\frac{1}{2}} ) helps apply exponent rules systematically. It's especially useful for more complex radical expressions.

Is this the same as squaring a square root?

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Exactly! 44=(4)2 \sqrt{4} \cdot \sqrt{4} = (\sqrt{4})^2 . When you square a square root, the operations cancel out, leaving just the number under the radical: (4)2=4 (\sqrt{4})^2 = 4 .

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