Solve x² + (x-2)² = 2(x+1)² : Multiple Squared Terms Equation

Quadratic Expansion with Like Term Cancellation

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 Find X
00:04 Use shortened multiplication formulas to open the parentheses
00:21 Group terms
00:41 Open parentheses properly, multiply by each term
00:51 Simplify what possible
00:56 Isolate X
01:16 And this is the solution to the problem

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

Solve the following equation. First, we'll simplify the algebraic expressions using the square of binomial formula:

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

Apply the mentioned formula and expand the parentheses in the expressions in the equation. On the right side, since we have parentheses with an exponent multiplier, we'll expand the (existing) parentheses using the square of binomial formula into additional parentheses (marked 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)x2+x24x+4=2x2+4x+2 x^2+(x-2)^2=2\underline{(x+1)^2} \\ 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) \\ x^2+x^2-4x+4=2x^2+4x+2 \\ In the final stage, we expand the parentheses on the right side by using the distributive property,

Continue to combine like terms, by moving terms between sides. We observe that the squared term cancels out, therefore it's a first-degree equation, which we'll solve by isolating the variable term on one side and dividing both sides of the equation by its coefficient:

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

In the final stage, we simplified the fraction that was obtained as the solution for x x .

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
  • Binomial Formula: Apply (a±b)² = a² ± 2ab + b² to all squared terms
  • Technique: Expand x² + (x-2)² = x² + x² - 4x + 4
  • Check: Substitute x = 1/4: 1/16 + 9/16 = 10/16 = 5/8 on both sides ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting to distribute the coefficient before expanding
    Don't expand 2(x+1)² as (2x+2)² = wrong result! The 2 is outside the parentheses, so you must first expand (x+1)² = x² + 2x + 1, then multiply by 2. Always expand the binomial first, then apply outside coefficients.

Practice Quiz

Test your knowledge with interactive questions

Declares the given expression as a sum

\( (7b-3x)^2 \)

FAQ

Everything you need to know about this question

Why did the x² terms cancel out completely?

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When you expand both sides, you get 2x24x+4=2x2+4x+2 2x^2 - 4x + 4 = 2x^2 + 4x + 2 . The 2x² terms are identical on both sides, so they subtract to zero, leaving a linear equation!

Do I always need to expand all the squared terms?

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Yes! You must expand every squared binomial using the formula (a±b)2=a2±2ab+b2 (a±b)^2 = a^2 ± 2ab + b^2 . Don't leave any parentheses unexpanded or you'll miss important terms.

What if I get confused with all the terms?

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Work step by step! First expand the left side completely, then the right side. Write each expansion on a separate line, then combine like terms carefully. Take your time!

How do I handle the coefficient 2 in front of (x+1)²?

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First expand (x+1)2=x2+2x+1 (x+1)^2 = x^2 + 2x + 1 , then multiply every term by 2: 2(x2+2x+1)=2x2+4x+2 2(x^2 + 2x + 1) = 2x^2 + 4x + 2

Why is the final answer a fraction?

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After combining like terms, you get 8x=2 -8x = -2 . Dividing both sides by -8 gives x=28=14 x = \frac{2}{8} = \frac{1}{4} . Always simplify your final fraction!

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