Solve the Equation: x⁴ + 2x² = 0 Using Factor Method

Quartic Equations with Zero Product Property

x4+2x2=0 x^4+2x^2=0

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:04 Factor with the X² term
00:15 Take out the common factor from the parentheses
00:18 This is one solution that zeros the equation
00:26 Now let's check which solutions zero the second factor
00:30 Isolate X
00:34 Any number squared is necessarily positive, therefore there is no solution
00:38 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

x4+2x2=0 x^4+2x^2=0

2

Step-by-step solution

To solve the equation x4+2x2=0x^4 + 2x^2 = 0, we will use the technique of factoring. Let's proceed step-by-step:

First, notice that both terms x4x^4 and 2x22x^2 have a common factor of x2x^2. We can factor x2x^2 out from the equation:

x2(x2+2)=0x^2(x^2 + 2) = 0

Now, to solve for xx, we apply the Zero Product Property, which gives us that at least one of the factors must be zero:

  • x2=0x^2 = 0 or
  • x2+2=0x^2 + 2 = 0

Solving the first case, x2=0x^2 = 0:

x=0x = 0

For the second case, x2+2=0x^2 + 2 = 0, we reach:

x2=2x^2 = -2

Since x2=2x^2 = -2 has no real solutions (squares of real numbers are non-negative), we can conclude that this equation doesn't provide additional real solutions.

Therefore, the only real solution to the given equation is x=0x = 0.

The correct choice from the provided options is:

x=0 x=0

3

Final Answer

x=0 x=0

Key Points to Remember

Essential concepts to master this topic
  • Factoring: Extract common factors before applying zero product property
  • Technique: Factor out x2 x^2 from x4+2x2=x2(x2+2)=0 x^4 + 2x^2 = x^2(x^2 + 2) = 0
  • Check: Substitute x = 0: 04+2(02)=0+0=0 0^4 + 2(0^2) = 0 + 0 = 0

Common Mistakes

Avoid these frequent errors
  • Forgetting to check for complex solutions
    Don't ignore the factor x2+2=0 x^2 + 2 = 0 completely = missing part of the analysis! While it gives no real solutions, recognizing this shows complete understanding. Always examine all factors even if they don't yield real solutions.

Practice Quiz

Test your knowledge with interactive questions

Solve the following equation:


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

FAQ

Everything you need to know about this question

Why can't I solve x² = -2 for real numbers?

+

Because squares of real numbers are always non-negative! When you square any real number (positive, negative, or zero), the result is always ≥ 0. Since -2 < 0, there's no real number that squares to -2.

What if I tried to solve this without factoring?

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You could substitute y=x2 y = x^2 to get y2+2y=0 y^2 + 2y = 0 , then factor as y(y+2)=0 y(y + 2) = 0 . This gives the same result but factoring directly is more efficient!

Are there other ways to factor this equation?

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Yes! You could write it as x2(x2+2)=0 x^2(x^2 + 2) = 0 or factor step by step. The key is recognizing the common factor of x2 x^2 in both terms.

Why is x = 0 the only real solution?

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From x2(x2+2)=0 x^2(x^2 + 2) = 0 , either x2=0 x^2 = 0 (giving x = 0) or x2+2=0 x^2 + 2 = 0 (giving x2=2 x^2 = -2 , which has no real solutions). So x = 0 is the only real answer!

How do I check if x = 0 is correct?

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Substitute back into the original equation: 04+2(02)=0+2(0)=0+0=0 0^4 + 2(0^2) = 0 + 2(0) = 0 + 0 = 0 . Since we get 0 = 0, our answer is correct!

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