Solve the Square Root Equation: √98/√x = 7

Square Root Equations with Algebraic Division

98x=7 \frac{\sqrt{98}}{\sqrt{x}}=7

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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 The square root of the number (A) divided by the square root of the number (B)
00:07 Is the same as the square root of the fraction (A divided by B)
00:10 We'll apply this formula to our exercise and proceed to convert to the root of a fraction
00:16 Square both sides in order to eliminate the fraction
00:26 Squaring cancels out the root
00:29 Calculate 7 squared
00:33 Isolate X
00:51 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

98x=7 \frac{\sqrt{98}}{\sqrt{x}}=7

2

Step-by-step solution

To solve this problem, let's proceed with the following steps:

  • Step 1: Start with the given equation:
    98x=7\frac{\sqrt{98}}{\sqrt{x}} = 7.
  • Step 2: Apply the square root property to combine the fraction:
    98x=7\sqrt{\frac{98}{x}} = 7.
  • Step 3: Square both sides to eliminate the square root:
    98x=49\frac{98}{x} = 49.
  • Step 4: Solve for x x by multiplying both sides by x x :
    98=49x98 = 49x.
  • Step 5: Isolate x x by dividing both sides by 49:
    x=9849x = \frac{98}{49}.
  • Step 6: Simplify the fraction:
    x=9849=2x = \frac{98}{49} = 2.

Therefore, the solution to the problem is x=2 x = 2 .

3

Final Answer

2 2

Key Points to Remember

Essential concepts to master this topic
  • Property: ab=ab \frac{\sqrt{a}}{\sqrt{b}} = \sqrt{\frac{a}{b}} for combining square root fractions
  • Technique: Square both sides to eliminate radicals: (98x)2=72 (\sqrt{\frac{98}{x}})^2 = 7^2
  • Check: Substitute x=2 x = 2 back: 982=7 \frac{\sqrt{98}}{\sqrt{2}} = 7

Common Mistakes

Avoid these frequent errors
  • Squaring only one side of the equation
    Don't square just 98x \sqrt{\frac{98}{x}} and leave 7 unchanged = equation becomes 98x=7 \frac{98}{x} = 7 instead of 49! This gives x=14 x = 14 which is wrong. Always square both sides simultaneously to maintain equality.

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 fraction?

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The property ab=ab \frac{\sqrt{a}}{\sqrt{b}} = \sqrt{\frac{a}{b}} works because division and square roots can be combined when both expressions are under the same radical. This makes the equation easier to solve!

What if x turns out to be negative?

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Since we have x \sqrt{x} in the denominator, x must be positive for the equation to be defined. Negative values would make the square root undefined in real numbers.

Do I always need to square both sides with square root equations?

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Usually yes, but be careful! Squaring can introduce extraneous solutions, so always check your answer by substituting back into the original equation.

How do I know 98/49 equals 2?

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Divide: 9849=2×4949=2 \frac{98}{49} = \frac{2 \times 49}{49} = 2 . You can also think of it as 98 ÷ 49 = 2 since 49 × 2 = 98.

Can I solve this without combining the square roots?

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Yes! You could multiply both sides by x \sqrt{x} first to get 98=7x \sqrt{98} = 7\sqrt{x} , then square both sides. Both methods work, but combining fractions is usually cleaner.

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