Solve the Equation: Square Root of 90 Divided by Square Root of x Equals 3

Radical Equations with Square Root Division

Solve the following equation:

90x=3 \frac{\sqrt{90}}{\sqrt{x}}=3

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:06 Let's find the value of X.
00:10 We take the square root of A, divided by the square root of B.
00:16 This is the same as taking the square root of A divided by B.
00:21 Now apply this to our problem. Convert to the square root of the fraction.
00:26 Next, we'll square the result to remove the root.
00:32 Squaring cancels the root, so calculate three squared.
00:36 Now, let's isolate X.
00:49 And there you have it! That's the solution.

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the following equation:

90x=3 \frac{\sqrt{90}}{\sqrt{x}}=3

2

Step-by-step solution

To solve this problem, we'll apply the properties of square roots and some straightforward algebraic techniques:

Step 1: Recall the equation given is:

90x=3 \frac{\sqrt{90}}{\sqrt{x}} = 3

Use the property of the square root quotient:

90x=3 \sqrt{\frac{90}{x}} = 3

Step 2: To eliminate the square root, square both sides of the equation:

(90x)2=32 \left(\sqrt{\frac{90}{x}}\right)^2 = 3^2

Thus, we have:

90x=9 \frac{90}{x} = 9

Step 3: Solve for xx by performing algebraic manipulation:

Multiply both sides by xx to remove the fraction:

90=9x 90 = 9x

Divide both sides by 9 to isolate xx:

x=909 x = \frac{90}{9}

Simplifying, we find:

x=10 x = 10

Therefore, the solution to the equation is x=10 x = 10 .

3

Final Answer

10

Key Points to Remember

Essential concepts to master this topic
  • Property: Square root quotient equals square root of quotient
  • Technique: Square both sides to eliminate radicals: (90x)2=32 (\sqrt{\frac{90}{x}})^2 = 3^2
  • Check: Substitute x = 10: 9010=31010=3 \frac{\sqrt{90}}{\sqrt{10}} = \frac{3\sqrt{10}}{\sqrt{10}} = 3

Common Mistakes

Avoid these frequent errors
  • Squaring only one side of the equation
    Don't square just 90x \sqrt{\frac{90}{x}} and leave 3 unchanged = wrong equation! This destroys the equality and gives incorrect solutions. Always square both sides simultaneously to maintain balance.

Practice Quiz

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Choose the largest value

FAQ

Everything you need to know about this question

Why can I combine the square roots in the quotient?

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The quotient property of square roots states that ab=ab \frac{\sqrt{a}}{\sqrt{b}} = \sqrt{\frac{a}{b}} . This property only works when both a and b are positive, which they are in this problem.

What happens when I square both sides?

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Squaring eliminates the square root because (something)2=something (\sqrt{something})^2 = something . However, always check your answer since squaring can sometimes introduce extra solutions that don't work in the original equation.

Can I solve this without combining the square roots first?

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Yes! You could multiply both sides by x \sqrt{x} first to get 90=3x \sqrt{90} = 3\sqrt{x} , then divide by 3 and square both sides. Both methods give x = 10.

How do I verify my answer is correct?

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Substitute x = 10 back into the original equation: 9010=90101010=90010=3010=3 \frac{\sqrt{90}}{\sqrt{10}} = \frac{\sqrt{90}}{\sqrt{10}} \cdot \frac{\sqrt{10}}{\sqrt{10}} = \frac{\sqrt{900}}{10} = \frac{30}{10} = 3

Why is the answer 10 and not 90?

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Remember we're solving for x in the denominator. When 90x=9 \frac{90}{x} = 9 , we get x = 10. The 90 in the numerator stays constant - we're finding what value of x makes the whole fraction equal to 9.

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