Solve the Equation: -2x(3-x)+(x-3)² = 9 for Parameter x

Quadratic Equations with Factoring Methods

Find the value of the parameter x.

2x(3x)+(x3)2=9 -2x(3-x)+(x-3)^2=9

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:09 Let's solve this problem step by step.
00:16 First, open the parentheses and multiply each factor inside.
00:26 Use the multiplication formulas to expand the parentheses.
00:39 Now, calculate the products from these multiplications.
00:47 Reduce by simplifying where possible.
00:52 Next, group similar terms together.
01:03 Break down each multiplication by using the factor three.
01:12 Take out the common factor from the entire expression.
01:25 Determine when each factor equals zero.
01:29 Then, isolate the unknown variable to find a solution.
01:34 That's one solution. Now, let's use the same method to find another one.
01:39 And there you have it. This is how we solve the problem!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Find the value of the parameter x.

2x(3x)+(x3)2=9 -2x(3-x)+(x-3)^2=9

2

Step-by-step solution

To solve the equation 2x(3x)+(x3)2=9-2x(3-x) + (x-3)^2 = 9, follow these steps:

  • Step 1: Expand each term:
    2x(3x)=6x+2x2-2x(3-x) = -6x + 2x^2 and (x3)2=x26x+9(x-3)^2 = x^2 - 6x + 9.
  • Step 2: Substitute the expanded terms into the equation:
    6x+2x2+x26x+9=9-6x + 2x^2 + x^2 - 6x + 9 = 9.
  • Step 3: Combine like terms:
    (2x2+x2)+(6x6x)+9=9(2x^2 + x^2) + (-6x - 6x) + 9 = 9.
  • Step 4: Simplify further:
    3x212x+9=93x^2 - 12x + 9 = 9.
  • Step 5: Move all terms to one side to form a quadratic equation:
    3x212x+99=03x^2 - 12x + 9 - 9 = 0.
  • Step 6: Simplify the expression:
    3x212x=03x^2 - 12x = 0.
  • Step 7: Factor out the common term:
    3x(x4)=03x(x - 4) = 0.
  • Step 8: Solve for x x :
    Since 3x=03x = 0 or x4=0x - 4 = 0, we find x=0x = 0 or x=4x = 4.

Therefore, the values of x x that satisfy the equation are x=0\mathbf{x = 0} and x=4\mathbf{x = 4}.

3

Final Answer

x=0,x=4 x=0,x=4

Key Points to Remember

Essential concepts to master this topic
  • Expansion: Multiply terms carefully: 2x(3x)=6x+2x2 -2x(3-x) = -6x + 2x^2
  • Factoring: Extract common factor: 3x212x=3x(x4) 3x^2 - 12x = 3x(x-4)
  • Check: Substitute x = 0: 2(0)(3)+(03)2=9 -2(0)(3) + (0-3)^2 = 9

Common Mistakes

Avoid these frequent errors
  • Incorrectly expanding the squared term
    Don't expand (x3)2 (x-3)^2 as x29 x^2 - 9 = missing the middle term! This gives 3x26x=0 3x^2 - 6x = 0 instead of 3x212x=0 3x^2 - 12x = 0 . Always use (ab)2=a22ab+b2 (a-b)^2 = a^2 - 2ab + b^2 for complete expansion.

Practice Quiz

Test your knowledge with interactive questions

Find the value of the parameter x.

\( (x-5)^2=0 \)

FAQ

Everything you need to know about this question

Why do I need to expand everything first?

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Expanding helps you combine like terms and see the equation's true form. Without expanding 2x(3x) -2x(3-x) and (x3)2 (x-3)^2 , you can't simplify to get the standard quadratic form.

How do I remember the formula for (x3)2 (x-3)^2 ?

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Use the pattern (ab)2=a22ab+b2 (a-b)^2 = a^2 - 2ab + b^2 . So (x3)2=x22(x)(3)+32=x26x+9 (x-3)^2 = x^2 - 2(x)(3) + 3^2 = x^2 - 6x + 9 . The middle term is always twice the product!

Why does 3x(x4)=0 3x(x-4) = 0 give me two answers?

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This uses the Zero Product Property: if two factors multiply to zero, at least one must be zero. So either 3x=0 3x = 0 (giving x = 0) or x4=0 x-4 = 0 (giving x = 4).

Can I solve this without factoring?

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Yes! You could use the quadratic formula on 3x212x=0 3x^2 - 12x = 0 , but factoring is much faster here since there's no constant term.

How do I check if both answers are correct?

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Substitute each value back into the original equation. For x = 0: 2(0)(3)+(03)2=0+9=9 -2(0)(3) + (0-3)^2 = 0 + 9 = 9 ✓. For x = 4: 2(4)(1)+(43)2=8+1=9 -2(4)(-1) + (4-3)^2 = 8 + 1 = 9

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