Solve (x-4)² + 3x² = -16x + 12: Multiple Squared Terms Equation

Quadratic Equations with Perfect Square Trinomials

Solve the following equation:

(x4)2+3x2=16x+12 (x-4)^2+3x^2=-16x+12

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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
00:21 Substitute appropriate values according to the given data and open the parentheses
00:37 Substitute into our equation
00:52 Arrange the equation so that one side equals 0
01:14 Collect like terms
01:38 Simplify as much as possible
01:51 Identify the coefficients
02:08 Use the root formula
02:20 Substitute appropriate values and solve
02:45 Calculate the squares and products
02:59 Root 0 always equals 0
03:04 When the root equals 0, there will be only one solution to the equation
03:26 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:

(x4)2+3x2=16x+12 (x-4)^2+3x^2=-16x+12

2

Step-by-step solution

To solve the given equation, follow these steps:

  • Step 1: Expand (x4)2(x - 4)^2 using the formula (ab)2=a22ab+b2(a - b)^2 = a^2 - 2ab + b^2.

Thus, (x4)2=x28x+16(x - 4)^2 = x^2 - 8x + 16.

  • Step 2: Substitute the expanded form into the equation:

x28x+16+3x2=16x+12x^2 - 8x + 16 + 3x^2 = -16x + 12.

  • Step 3: Combine like terms on the left-hand side.

This gives 4x28x+16=16x+124x^2 - 8x + 16 = -16x + 12.

  • Step 4: Rearrange the equation to set it to zero.

Bring all terms to one side: 4x28x+16+16x12=04x^2 - 8x + 16 + 16x - 12 = 0.

Combine and simplify the terms: 4x2+8x+4=04x^2 + 8x + 4 = 0.

  • Step 5: Simplify the equation by dividing each term by 4.

It becomes x2+2x+1=0x^2 + 2x + 1 = 0.

  • Step 6: Recognize the equation as a perfect square trinomial.

(x+1)2=0(x + 1)^2 = 0.

  • Step 7: Solve by taking the square root of both sides.

The solution is x+1=0x + 1 = 0, therefore x=1x = -1.

In conclusion, the solution to the equation is x=1 x = -1 .

3

Final Answer

x=1 x=-1

Key Points to Remember

Essential concepts to master this topic
  • Expansion Rule: Use (ab)2=a22ab+b2 (a-b)^2 = a^2 - 2ab + b^2 to expand squared binomials
  • Technique: Combine like terms: x2+3x2=4x2 x^2 + 3x^2 = 4x^2 before rearranging
  • Check: Substitute x=1 x = -1 : (14)2+3(1)2=25+3=28 (-1-4)^2 + 3(-1)^2 = 25 + 3 = 28 and 16(1)+12=28 -16(-1) + 12 = 28

Common Mistakes

Avoid these frequent errors
  • Incorrectly expanding the squared binomial
    Don't expand (x4)2 (x-4)^2 as x216 x^2 - 16 = missing the middle term! This gives completely wrong coefficients. Always remember (x4)2=x28x+16 (x-4)^2 = x^2 - 8x + 16 using the full formula.

Practice Quiz

Test your knowledge with interactive questions

\( (4b-3)(4b-3) \)

Rewrite the above expression as an exponential summation expression:

FAQ

Everything you need to know about this question

Why does (x4)2 (x-4)^2 have three terms when expanded?

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The formula (ab)2=a22ab+b2 (a-b)^2 = a^2 - 2ab + b^2 always gives three terms. So (x4)2=x22(x)(4)+42=x28x+16 (x-4)^2 = x^2 - 2(x)(4) + 4^2 = x^2 - 8x + 16 . Never forget that middle term!

How do I know when I have a perfect square trinomial?

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Look for the pattern a2+2ab+b2 a^2 + 2ab + b^2 or a22ab+b2 a^2 - 2ab + b^2 . In our case, x2+2x+1=(x+1)2 x^2 + 2x + 1 = (x+1)^2 because the middle term is twice the product of the square roots.

Can a quadratic equation have only one solution?

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Yes! When the discriminant equals zero, you get a repeated root. Here, (x+1)2=0 (x+1)^2 = 0 means x=1 x = -1 is a double root - the parabola just touches the x-axis at one point.

What if I can't factor the trinomial easily?

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Use the quadratic formula: x=b±b24ac2a x = \frac{-b \pm \sqrt{b^2-4ac}}{2a} . For x2+2x+1=0 x^2 + 2x + 1 = 0 , you get x=2±442=1 x = \frac{-2 \pm \sqrt{4-4}}{2} = -1 .

Why do we move everything to one side?

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Setting the equation to zero is the standard form for solving quadratics. It allows us to factor, complete the square, or use the quadratic formula. Always rearrange to get ax2+bx+c=0 ax^2 + bx + c = 0 first!

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