Solve the Equation: x²+(x-2)²=2(x+1)² with Square Binomials

Quadratic Equations with Perfect Square Binomials

Solve the following problem:

x2+(x2)2=2(x+1)2 x^2+(x-2)^2=2(x+1)^2

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:03 We'll use shortened multiplication formulas to open the parentheses
00:16 Collect like terms
00:23 Open parentheses properly, multiply by each term
00:36 Simplify where possible
00:41 Isolate X
01:03 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the following problem:

x2+(x2)2=2(x+1)2 x^2+(x-2)^2=2(x+1)^2

2

Step-by-step solution

Examine the given equation:

x2+(x2)2=2(x+1)2 x^2+(x-2)^2=2(x+1)^2

Start by simplifying the equation, to achieve this we'll apply the perfect square formula for a binomial squared:

(a±b)2=a2±2ab+b2 (a\pm b)^2=a^2\pm2ab+b^2 ,

Start by opening the parentheses on both sides simultaneously using the perfect square formula, then proceed to combine like terms,

Note that according to the order of operations (which prioritizes exponents over multiplication), the expression inside of the right-hand parentheses is first squared and then the resulting expression is multiplied by 2,

Therefore, the expression that we obtain from applying the perfect square formula on the right-hand side will be placed in parentheses which we'll multiply by 2 (highlighted with an underline in the following calculation):

x2+(x2)2=2(x+1)2x2+x22x2+22=2(x2+2x1+12)x2+x24x+4=2(x2+2x+1) x^2+(x-2)^2=2\underline{(x+1)^2} \\ \downarrow\\ x^2+x^2-2\cdot x\cdot2+2^2=2\underline{(x^2+2\cdot x\cdot1+1^2)}\\ x^2+x^2-4x+4=2(x^2+2x+1)\\ Let's continue, open the parentheses on the right side by using the distributive property, move and combine like terms. In the final step we'll solve the simplified equation that we obtain

x2+x24x+4=2(x2+2x+1)2x24x+4=2x2+4x+28x=2/:(-8)x=28x=14 x^2+x^2-4x+4=2(x^2+2x+1)\\ 2x^2-4x+4=2x^2+4x+2\\ -8x=-2\hspace{6pt}\text{/:(-8)}\\ x=\frac{-2}{-8}\\ \downarrow\\ \boxed{x=\frac{1}{4}}

In the final step we reduced the fraction that we obtained as the solution for the unknown,

Therefore the correct answer is answer B.

3

Final Answer

x=14 x=\frac{1}{4}

Key Points to Remember

Essential concepts to master this topic
  • Formula: Apply (a±b)2=a2±2ab+b2 (a\pm b)^2 = a^2 \pm 2ab + b^2 to expand binomials
  • Technique: Expand (x2)2=x24x+4 (x-2)^2 = x^2 - 4x + 4 before combining terms
  • Check: Substitute x=14 x = \frac{1}{4} : both sides equal 418 \frac{41}{8}

Common Mistakes

Avoid these frequent errors
  • Forgetting to distribute the coefficient before expanding
    Don't expand 2(x+1)² as 2x² + 4x + 2 = wrong distribution! This ignores that you must first expand (x+1)² to get x² + 2x + 1, then multiply everything by 2. Always expand the binomial first, then distribute the coefficient.

Practice Quiz

Test your knowledge with interactive questions

\( x^2+6x+9=0 \)

What is the value of X?

FAQ

Everything you need to know about this question

Why do I need to expand the binomials instead of just solving directly?

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Expanding binomials using the perfect square formula converts the equation into standard form, making it easier to combine like terms and solve. Without expanding, you can't simplify the equation properly.

How do I remember the perfect square formula correctly?

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Remember (a±b)2=a2±2ab+b2 (a \pm b)^2 = a^2 \pm 2ab + b^2 : first squared, plus/minus twice the product, plus second squared. Practice with simple examples like (x+3)2=x2+6x+9 (x+3)^2 = x^2 + 6x + 9 .

What's the order of operations when I have 2(x+1)²?

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Follow PEMDAS: First expand the parentheses and exponent (x+1)2 (x+1)^2 , then multiply the result by 2. Don't multiply 2 by each term inside the parentheses first!

How can I check if my final answer is correct?

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Substitute your answer back into the original equation. For x=14 x = \frac{1}{4} , both sides should give the same value when you calculate them completely.

Why did I get a fraction as my answer?

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Fractional answers are completely normal in algebra! Many equations have solutions that aren't whole numbers. Just make sure to simplify your fraction to lowest terms like 28=14 \frac{2}{8} = \frac{1}{4} .

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