Solve Nested Square Roots: √√49 × √√16 Multiplication Problem

Nested Square Roots with Perfect Square Bases

Complete the following exercise:

4916= \sqrt{\sqrt{49}}\cdot\sqrt{\sqrt{16}}=

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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 Break down 49 to 7 squared
00:11 Break down 16 to 4 squared
00:18 The square root of any number (A) squared cancels out the square
00:22 Let's apply this formula to our exercise and proceed to cancel out the squares:
00:35 Break down 4 to 2 squared
00:40 The square root cancels the square
00:45 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Complete the following exercise:

4916= \sqrt{\sqrt{49}}\cdot\sqrt{\sqrt{16}}=

2

Step-by-step solution

To find the value of 4916 \sqrt{\sqrt{49}} \cdot \sqrt{\sqrt{16}} , we will follow these steps:

  • Step 1: Simplify 49 \sqrt{\sqrt{49}} .
  • Step 2: Simplify 16 \sqrt{\sqrt{16}} .
  • Step 3: Multiply the simplified results together.

Step 1: 49\sqrt{\sqrt{49}}
- Calculate 49=7\sqrt{49} = 7.
- Therefore, 49=7\sqrt{\sqrt{49}} = \sqrt{7}.

Step 2: 16\sqrt{\sqrt{16}}
- Calculate 16=4\sqrt{16} = 4.
- Therefore, 16=4=2\sqrt{\sqrt{16}} = \sqrt{4} = 2.

Step 3: Multiply the simplified results:
- Multiply 7\sqrt{7} by 22.
- The product is 27=272 \cdot \sqrt{7} = 2\sqrt{7}.

Therefore, the value of 4916 \sqrt{\sqrt{49}} \cdot \sqrt{\sqrt{16}} is 27\mathbf{2\sqrt{7}}.

3

Final Answer

27 2\sqrt{7}

Key Points to Remember

Essential concepts to master this topic
  • Order Rule: Always work from inside out on nested radicals
  • Technique: 49=7 \sqrt{\sqrt{49}} = \sqrt{7} and 16=4=2 \sqrt{\sqrt{16}} = \sqrt{4} = 2
  • Check: Verify 27 2\sqrt{7} by computing (27)2=47=28 (2\sqrt{7})^2 = 4 \cdot 7 = 28

Common Mistakes

Avoid these frequent errors
  • Trying to multiply under one radical
    Don't combine as 4916 \sqrt{\sqrt{49} \cdot \sqrt{16}} = wrong approach! This skips the crucial step of evaluating each nested radical first. Always simplify each n \sqrt{\sqrt{n}} separately before multiplying.

Practice Quiz

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Choose the largest value

FAQ

Everything you need to know about this question

Why can't I just multiply 49 × 16 under the radicals?

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Because 4916 \sqrt{\sqrt{49}} \cdot \sqrt{\sqrt{16}} is not the same as 49×16 \sqrt{\sqrt{49 \times 16}} ! You must evaluate each nested radical separately first.

How do I know when to stop taking square roots?

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Work from the innermost radical outward. For 16 \sqrt{\sqrt{16}} : first find 16=4 \sqrt{16} = 4 , then 4=2 \sqrt{4} = 2 . Stop when you can't simplify further.

What if the inner square root isn't a perfect square?

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Like with 49 \sqrt{\sqrt{49}} ! Since 49=7 \sqrt{49} = 7 and 7 isn't a perfect square, you get 7 \sqrt{7} and leave it in radical form.

Can I use a calculator for nested square roots?

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Yes, but be careful! For 49 \sqrt{\sqrt{49}} , calculate 49=7 \sqrt{49} = 7 first, then 72.646 \sqrt{7} \approx 2.646 . But keep exact answers like 27 2\sqrt{7} when possible.

Why is the answer 27 2\sqrt{7} and not just a decimal?

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Because 7 \sqrt{7} is irrational (never-ending, non-repeating decimal). The exact answer 27 2\sqrt{7} is more precise than any decimal approximation!

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