Solve for X: Simplifying √20·√5/x = 2√25 Equation

Radical Equations with Product Rule Simplification

Solve for x:

205x=225 \frac{\sqrt{20}\cdot\sqrt{5}}{x}=2\cdot\sqrt{25}

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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 Isolate X
00:28 When multiplying a square root of a number (A) by a square root of another number (B)
00:32 The result equals the square root of their product (A times B)
00:37 Apply this formula to our exercise and calculate the product
00:44 Break down 100 into 10 squared
00:48 Break down 25 into 5 squared
00:51 Every square root of a number (A) squared equals the number itself (A)
00:54 Apply this formula to our exercise and cancel out the squares
01:05 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:

205x=225 \frac{\sqrt{20}\cdot\sqrt{5}}{x}=2\cdot\sqrt{25}

2

Step-by-step solution

To solve the equation \<205x=225\frac{\sqrt{20}\cdot\sqrt{5}}{x} = 2\cdot\sqrt{25}\>, follow these steps:

  • Step 1: Simplify the left-hand side.
    - Use the product rule for roots: 205=205=100\sqrt{20} \cdot \sqrt{5} = \sqrt{20 \cdot 5} = \sqrt{100}.
  • Step 2: Simplify 100\sqrt{100} to get 10\.
  • Step 3: Substitute and simplify the equation:
    \(\frac{10}{x} = 2 \cdot \sqrt{25}.
  • Step 4: Simplify the right-hand side:
    25=5\sqrt{25} = 5 so 25=102 \cdot 5 = 10.
  • Step 5: Equate both sides:
    10x=10\frac{10}{x} = 10.
  • Step 6: Solve for xx:
    Multiply both sides by xx, then divide by 10:
    10=10x10 = 10x produces x=1x = 1.

Therefore, the solution to the problem is x=1\boldsymbol{x = 1}.

3

Final Answer

1 1

Key Points to Remember

Essential concepts to master this topic
  • Product Rule: Combine radicals: 205=100=10 \sqrt{20} \cdot \sqrt{5} = \sqrt{100} = 10
  • Technique: Simplify both sides first: 225=25=10 2\sqrt{25} = 2 \cdot 5 = 10
  • Check: Substitute x = 1 back: 101=10 \frac{10}{1} = 10 matches 225=10 2\sqrt{25} = 10

Common Mistakes

Avoid these frequent errors
  • Solving without simplifying radicals first
    Don't leave 205 \sqrt{20} \cdot \sqrt{5} unsimplified = confusing work with wrong setup! This makes the equation unnecessarily complex and increases calculation errors. Always use the product rule to simplify ab=ab \sqrt{a} \cdot \sqrt{b} = \sqrt{ab} before solving.

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

Can I multiply the square roots directly like regular numbers?

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Yes, but with the product rule! When multiplying square roots, use ab=ab \sqrt{a} \cdot \sqrt{b} = \sqrt{a \cdot b} . So 205=20×5=100=10 \sqrt{20} \cdot \sqrt{5} = \sqrt{20 \times 5} = \sqrt{100} = 10 .

What if I can't simplify the square root to a whole number?

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That's okay! Not all square roots simplify to whole numbers. Just make sure to combine them correctly using the product rule, then work with the simplified form throughout your solution.

How do I know when to use the product rule for square roots?

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Use the product rule whenever you see two or more square roots being multiplied. This lets you combine them into one radical, making calculations much easier!

Why did we get x = 1 as the answer?

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After simplifying both sides to 10, we had 10x=10 \frac{10}{x} = 10 . Cross-multiplying gives us 10=10x 10 = 10x , so x=1 x = 1 . Always verify by substituting back!

What's the difference between √25 and 2√25?

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25=5 \sqrt{25} = 5 (just the square root), but 225=2×5=10 2\sqrt{25} = 2 \times 5 = 10 (multiply by 2). The coefficient multiplies the entire radical value.

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