Solve the Symmetric Squares Equation: (1 - x)² = (2x + 1)²

Quadratic Equations with Square Root Property

Solve the following equation:

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

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:03 Use the shortened multiplication formulas
00:17 Substitute appropriate values and expand the brackets
00:34 Substitute in our equation
00:41 Use the same method to expand the second brackets
01:16 Substitute in our equation
01:23 Arrange the equation so that one side equals 0
01:45 Collect like terms
02:05 Factor X squared into X and X
02:08 Factor 6 into 3 and 2
02:13 Find the greatest common factor
02:20 Take out this factor from the brackets
02:27 Find what makes each factor equal zero
02:35 Isolate X, this is one solution
02:43 Find what makes the second factor equal zero
02:46 Isolate X
02:51 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 equation:

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

2

Step-by-step solution

To solve the equation (x+1)2=(2x+1)2 (-x+1)^2=(2x+1)^2 , we will follow these steps:

  • Step 1: Recognize the equation as an application of the identity a2=b2 a^2 = b^2 . This implies a=b a = b or a=b a = -b .
  • Step 2: Apply the identity to our equation.
  • Step 3: Solve each of the resulting equations individually to find the possible values of x x .

Now, let's perform each step in detail:

Step 1: We have the equation (x+1)2=(2x+1)2 (-x+1)^2 = (2x+1)^2 . According to the identity a2=b2 a^2 = b^2 , we can set up the following cases:
Case 1: x+1=2x+1 -x + 1 = 2x + 1 ,
Case 2: x+1=(2x+1) -x + 1 = -(2x + 1) .

Step 2: Solve Case 1:
From x+1=2x+1 -x + 1 = 2x + 1 , subtract 1 from both sides: x=2x -x = 2x .
Adding x x to both sides gives 0=3x 0 = 3x .
Divide by 3: x=0 x = 0 .

Step 3: Solve Case 2:
From x+1=(2x+1) -x + 1 = -(2x + 1) , distribute the negative sign on the right: x+1=2x1 -x + 1 = -2x - 1 .
Add 2x 2x to both sides: x+1=1 x + 1 = -1 .
Subtract 1 from both sides: x=2 x = -2 .

Therefore, the solutions to the equation are x1=0 x_1=0 and x2=2 x_2=-2 .

The correct answer is:

x1=0,x2=2 x_1=0,x_2=-2

3

Final Answer

x1=0,x2=2 x_1=0,x_2=-2

Key Points to Remember

Essential concepts to master this topic
  • Rule: When a² = b², then a = b or a = -b
  • Technique: Set up two cases: (-x+1) = (2x+1) and (-x+1) = -(2x+1)
  • Check: Substitute x = 0 and x = -2: both make equation true ✓

Common Mistakes

Avoid these frequent errors
  • Expanding both squared terms instead of using the square root property
    Don't expand (-x+1)² = x² - 2x + 1 and (2x+1)² = 4x² + 4x + 1 to get a messy quadratic! This creates unnecessary complexity and increases calculation errors. Always use the property: if a² = b², then a = b or a = -b.

Practice Quiz

Test your knowledge with interactive questions

Solve the following exercise:

\( 2x^2-8=x^2+4 \)

FAQ

Everything you need to know about this question

Why do I get two equations from one?

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When a2=b2 a^2 = b^2 , there are two possibilities: either the expressions are equal (a = b) or they are opposites (a = -b). Both cases make the squares equal!

What if I expand the squares instead?

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You can expand, but it's much harder! You'd get x22x+1=4x2+4x+1 x^2 - 2x + 1 = 4x^2 + 4x + 1 , leading to 3x2+6x=0 3x^2 + 6x = 0 . The square root property is much faster.

How do I know which case gives which solution?

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Solve both cases separately! Case 1: x+1=2x+1 -x + 1 = 2x + 1 gives x = 0. Case 2: x+1=(2x+1) -x + 1 = -(2x + 1) gives x = -2.

Do I always get exactly two solutions?

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Not always! Sometimes the two cases give the same solution (one repeated root), or one case might have no solution. Always solve both cases to find out.

How can I check my answers quickly?

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Substitute each solution back into the original equation. For x = 0: (1)2=(1)2 (1)^2 = (1)^2 ✓. For x = -2: (3)2=(3)2 (3)^2 = (-3)^2

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