Solve: 8(x-√3)(√3+x)=2x² | Square Root and Quadratic Equation

Quadratic Equations with Difference of Squares

8(x3)(3+x)=2x2 8(x-\sqrt{3})(\sqrt{3}+x)=2x^2

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:09 Use the shortened multiplication formulas
00:21 Use the commutative law
00:37 Use the shortened multiplication formulas and write the expression
00:45 Calculate the square of root 3
00:54 Divide by 2
01:04 Open parentheses properly
01:16 Arrange the equation so that 0 is on the right side
01:28 Divide by 3
01:38 Convert from p to square of 2
01:43 Again use the shortened multiplication formulas
01:49 To find the two possible solutions
02:01 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

8(x3)(3+x)=2x2 8(x-\sqrt{3})(\sqrt{3}+x)=2x^2

2

Step-by-step solution

To solve the equation 8(x3)(3+x)=2x2 8(x-\sqrt{3})(\sqrt{3}+x) = 2x^2 , follow these steps:

  • Step 1: Simplify the left side using the difference of squares, which states (ab)(a+b)=a2b2(a-b)(a+b)=a^2-b^2. Here, we treat a=x a = x and b=3 b = \sqrt{3} . This gives us:

(x3)(3+x)=x2(3)2=x23(x-\sqrt{3})(\sqrt{3}+x) = x^2 - (\sqrt{3})^2 = x^2 - 3

  • Step 2: Multiply this by 8 as the equation is 8(x23) 8(x^2 - 3) .

This results in: 8(x23)=8x224 8(x^2 - 3) = 8x^2 - 24

  • Step 3: Substitute this into the equation to get: 8x224=2x2 8x^2 - 24 = 2x^2 .
  • Step 4: Rearrange terms and solve for x x by bringing all terms to one side:

8x22x224=0 8x^2 - 2x^2 - 24 = 0 which simplifies to 6x224=0 6x^2 - 24 = 0 .

  • Step 5: Factor out the common terms in the quadratic equation:

6(x24)=0 6(x^2 - 4) = 0

  • Step 6: Notice that using the difference of squares again, x24 x^2 - 4 factors to (x2)(x+2)(x-2)(x+2).

This yields: 6(x2)(x+2)=0 6(x-2)(x+2) = 0 .

  • Step 7: Solve (x2)(x+2)=0 (x - 2)(x + 2) = 0 and apply the zero product property:

This gives the solutions x2=0 x - 2 = 0 and x+2=0 x + 2 = 0 , thus x=2 x = 2 and x=2 x = -2 .

Therefore, the solution to the problem is ±2 \pm2 .

3

Final Answer

±2 \pm2

Key Points to Remember

Essential concepts to master this topic
  • Pattern Recognition: Identify (ab)(a+b)=a2b2 (a-b)(a+b) = a^2 - b^2 for factoring
  • Technique: (x3)(x+3)=x23 (x-\sqrt{3})(x+\sqrt{3}) = x^2 - 3 simplifies the left side
  • Check: Substitute x = 2: 8(43)=8 8(4-3) = 8 and 2(4)=8 2(4) = 8

Common Mistakes

Avoid these frequent errors
  • Expanding binomials term by term instead of recognizing difference of squares
    Don't multiply (x3)(3+x) (x-\sqrt{3})(\sqrt{3}+x) as x3+x23x3 x\sqrt{3} + x^2 - 3 - x\sqrt{3} = messy algebra! This creates unnecessary complexity and increases error risk. Always look for the pattern (ab)(a+b)=a2b2 (a-b)(a+b) = a^2 - b^2 first.

Practice Quiz

Test your knowledge with interactive questions

Solve:

\( (2+x)(2-x)=0 \)

FAQ

Everything you need to know about this question

How do I recognize when to use difference of squares?

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Look for the pattern (ab)(a+b) (a-b)(a+b) ! When you see two binomials with the same terms but opposite signs in the middle, use a2b2 a^2 - b^2 instead of expanding.

What if the terms aren't in the right order like in this problem?

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No problem! (x3)(3+x) (x-\sqrt{3})(\sqrt{3}+x) is the same as (x3)(x+3) (x-\sqrt{3})(x+\sqrt{3}) because addition is commutative. Just rearrange to see the pattern clearly.

Why does (3)2=3 (\sqrt{3})^2 = 3 ?

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By definition, square root means the number that when multiplied by itself gives the original number. So 3×3=3 \sqrt{3} \times \sqrt{3} = 3 , which we write as (3)2=3 (\sqrt{3})^2 = 3 .

How do I solve 6x224=0 6x^2 - 24 = 0 quickly?

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Factor out the GCF first: 6(x24)=0 6(x^2 - 4) = 0 . Then recognize x24 x^2 - 4 as another difference of squares: (x2)(x+2)=0 (x-2)(x+2) = 0 !

Why do I get two answers for this quadratic?

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Quadratic equations typically have two solutions because you're finding where a parabola crosses the x-axis. The zero product property tells us if (x2)(x+2)=0 (x-2)(x+2) = 0 , then either x=2 x = 2 or x=2 x = -2 .

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