Quadratic Conundrum: Solving 2x² - 8 = x^2 + 4

Question

Solve the following equation:


2x28=x2+4 2x^2-8=x^2+4

Video Solution

Solution Steps

00:00 Find X
00:03 Isolate X
00:29 Extract root
00:32 When extracting a root there are always 2 solutions (positive, negative)
00:35 And this is the solution to the question

Step-by-Step Solution

Let's solve the equation step-by-step:

  • Step 1: Rearrange the equation.

We start with the given equation:

2x28=x2+42x^2 - 8 = x^2 + 4

Subtract x2+4x^2 + 4 from both sides to get:

2x28x24=02x^2 - 8 - x^2 - 4 = 0

  • Step 2: Simplify the equation.

Combine the like terms:

(2x2x2)84=0(2x^2 - x^2) - 8 - 4 = 0

This simplifies to:

x212=0x^2 - 12 = 0

  • Step 3: Solve for xx.

Add 12 to both sides:

x2=12x^2 = 12

Now take the square root of both sides:

x=±12x = \pm \sqrt{12}

Given the choices, the correct answer is ±12\pm \sqrt{12}.

Answer

±12 ±\sqrt{12}