Solve for X: Finding Solutions to x²/10 - 10 = 0

Quadratic Equations with Fractional Forms

x21010=0 \frac{x^2}{10}-10=0

Solve the above equation for X.

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:07 Let's find X.
00:10 First, we need to isolate the variable X.
00:24 Remember, when a number is multiplied by itself, it's squared.
00:29 Now, we extract the square root.
00:32 Keep in mind, extracting a root gives us two solutions: a positive and a negative.
00:37 And that's how we solve for X. Great job!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

x21010=0 \frac{x^2}{10}-10=0

Solve the above equation for X.

2

Step-by-step solution

Let's solve the given equation:

x21010=0 \frac{x^2}{10}-10=0

Begin by eliminating the fraction line on the left side of the given equation. It is possible to achieve this by multiplying both sides of the equation by the common denominator - which is the number 10, then we'll move the free number to one side, remembering that when moving a term between sides - its sign changes:

x210101=0/101x21010=0x2100=0x2=100 \frac{x^2}{10}-\frac{10}{1}=0\hspace{8pt}\text{/}\cdot 10\\ \\ 1\cdot x^2-10\cdot10=0 \\ x^2-100=0\\ x^2=100

From here, perform on both sides the opposite operation to the square power operation applied to the unknown in the equation, which is the square root operation, using the laws of exponents:

a. Definition of root as a power:

an=a1n \sqrt[n]{a}=a^{\frac{1}{n}} and the two laws of exponents:

b. Law of exponents for power of a power:

(am)n=amn (a^m)^n=a^{m\cdot n}

Let's continue solving the equation:
x2=100/x2=±100(x2)12=±10x212=±10x=10,10 x^2=100\hspace{8pt}\text{/}\sqrt{\hspace{6pt}}\\ \sqrt{ x^2}=\pm\sqrt{ 100}\\ (x^2)^{\frac{1}{2}}=\pm10\\ x^{2\cdot\frac{1}{2}}=\pm10\\ \boxed{x=10,-10}

In the first stage, we applied the square root to both sides of the equation. We then applied the definition of root as a power (a.) on the left side, in the next stage - we applied the law of exponents for power of a power (b.) on the left side, and remembered that raising a number to the power of 1 doesn't change the number.

Additionally, given that an even power doesn't preserve the sign of the number it's applied to (it will always give a positive result), taking an even root of both sides of the equation requires considering two possible cases - positive and negative (this is unlike taking a root of an odd order, which requires considering only one case that matches the sign of the number the root is applied to),

Let's summarize the solution of the equation:

x21010=0/10x2=100/x=10,10 \frac{x^2}{10}-10=0 \hspace{8pt}\text{/}\cdot 10\\ x^2=100 \hspace{8pt}\text{/}\sqrt{\hspace{6pt}}\\ \boxed{x=10,-10}

Therefore, the correct answer is answer a.

3

Final Answer

x=±10 x=\pm10

Key Points to Remember

Essential concepts to master this topic
  • Clear Fractions: Multiply both sides by 10 to eliminate denominators
  • Isolate Variable: Add 100 to both sides: x2=100 x^2 = 100
  • Check Solutions: Substitute ±10 back: (±10)21010=0 \frac{(±10)^2}{10} - 10 = 0

Common Mistakes

Avoid these frequent errors
  • Forgetting the ± when taking square roots
    Don't write x = 10 as the only solution = missing half the answer! When you take the square root of both sides, both positive and negative values squared give the same result. Always write x = ±10 for complete solutions.

Practice Quiz

Test your knowledge with interactive questions

Complete the corresponding expression for the denominator

\( \frac{12ab}{?}=1 \)

FAQ

Everything you need to know about this question

Why do I get two answers for this equation?

+

Because squaring eliminates signs! Both 10² and (-10)² equal 100. When you reverse the squaring with square roots, you must consider both the positive and negative possibilities.

Should I multiply by 10 first or move the -10 first?

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Either works! You can multiply by 10 first to get x2100=0 x^2 - 100 = 0 , or add 10 first to get x210=10 \frac{x^2}{10} = 10 . Choose what feels easier!

How do I know when to use the ± symbol?

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Use ± whenever you take an even root (like square root, 4th root) of both sides. Odd roots don't need ± because they preserve the original sign.

What if I forgot to clear the fraction?

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You can still solve it! Just multiply both sides by 10 at the end: x210=10 \frac{x^2}{10} = 10 becomes x2=100 x^2 = 100 . The fraction-clearing step just makes calculations cleaner.

Can I check my work without substituting back?

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Substitution is the most reliable check, but you can also verify that (±10)2=100 (±10)^2 = 100 and 1001010=0 \frac{100}{10} - 10 = 0 makes sense.

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