Solve for X: Simplifying √8·√4·√2/√2 = √(x²)

Radical Simplification with Product Rules

Solve for x:

8422=x2 \frac{\sqrt{8}\cdot\sqrt{4}\cdot\sqrt{2}}{\sqrt{2}}=\sqrt{x^2}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find the value X
00:03 Simplify wherever possible
00:11 When multiplying the root of a number (A) by the root of another number (B)
00:14 The result equals the root of their product (A times B)
00:18 Apply this formula to our exercise
00:26 Any root of a number (A) squared equals the number itself (A)
00:30 Apply this formula to our exercise, and cancel out the square:
00:34 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve for x:

8422=x2 \frac{\sqrt{8}\cdot\sqrt{4}\cdot\sqrt{2}}{\sqrt{2}}=\sqrt{x^2}

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Simplify the expression 842\sqrt{8}\cdot\sqrt{4}\cdot\sqrt{2}.
  • Divide this product by 2\sqrt{2}.
  • Set the result equal to x2\sqrt{x^2} and solve for x x .

Now, let's work through each step:

Step 1: First, simplify the product under the square root:

842=842\sqrt{8}\cdot\sqrt{4}\cdot\sqrt{2} = \sqrt{8\cdot4\cdot2}.

This simplifies to:

64\sqrt{64}, because 842=648 \cdot 4 \cdot 2 = 64.

Step 2: Now, divide by 2\sqrt{2}:

642=642=32\frac{\sqrt{64}}{\sqrt{2}} = \sqrt{\frac{64}{2}} = \sqrt{32}.

Step 3: Equate this to x2\sqrt{x^2}:

32=x2\sqrt{32} = \sqrt{x^2}.

This implies x=32 |x| = \sqrt{32} , giving us two possible solutions: x=32 x = \sqrt{32} and x=32 x = -\sqrt{32} .

Since the simplification naturally leads to positive expressions, we find:

The solution is x=32 x = \sqrt{32} .

3

Final Answer

x=32 x=\sqrt{32}

Key Points to Remember

Essential concepts to master this topic
  • Product Rule: Multiply radicals by combining under one radical sign
  • Technique: ab=ab \sqrt{a} \cdot \sqrt{b} = \sqrt{a \cdot b} , so 842=64 \sqrt{8} \cdot \sqrt{4} \cdot \sqrt{2} = \sqrt{64}
  • Check: Verify 32=x2 \sqrt{32} = \sqrt{x^2} means x=32 |x| = \sqrt{32}

Common Mistakes

Avoid these frequent errors
  • Adding instead of multiplying under the radical
    Don't write 842=8+4+2=14 \sqrt{8} \cdot \sqrt{4} \cdot \sqrt{2} = \sqrt{8+4+2} = \sqrt{14} ! This gives the wrong answer because you're adding instead of multiplying. Always use the product rule: ab=ab \sqrt{a} \cdot \sqrt{b} = \sqrt{a \cdot b} .

Practice Quiz

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Choose the largest value

FAQ

Everything you need to know about this question

Why can I combine all the square roots under one radical?

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The product rule for radicals says ab=ab \sqrt{a} \cdot \sqrt{b} = \sqrt{a \cdot b} . This works because both expressions represent the same value - the positive number that when squared gives you the product inside.

How do I divide square roots like 642 \frac{\sqrt{64}}{\sqrt{2}} ?

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Use the quotient rule: ab=ab \frac{\sqrt{a}}{\sqrt{b}} = \sqrt{\frac{a}{b}} . So 642=642=32 \frac{\sqrt{64}}{\sqrt{2}} = \sqrt{\frac{64}{2}} = \sqrt{32} .

Why does x2 \sqrt{x^2} equal x |x| and not just x?

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Because x2 \sqrt{x^2} always gives the positive square root. For example, if x = -5, then (5)2=25=5 \sqrt{(-5)^2} = \sqrt{25} = 5 , not -5. That's why we write x |x| to include both positive and negative solutions.

Should I leave my answer as 32 \sqrt{32} or simplify it further?

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You can simplify further! 32=162=42 \sqrt{32} = \sqrt{16 \cdot 2} = 4\sqrt{2} . However, since the answer choices show 32 \sqrt{32} , either form is correct.

What if I calculated 842 8 \cdot 4 \cdot 2 wrong?

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Double-check your multiplication step by step: 8×4=32 8 \times 4 = 32 , then 32×2=64 32 \times 2 = 64 . Getting the wrong product here will mess up your entire answer!

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