(x+3)^4+2(x+3)^2-8=0

2 min read Jun 16, 2024
(x+3)^4+2(x+3)^2-8=0

Solving the Equation (x+3)^4 + 2(x+3)^2 - 8 = 0

This equation might look intimidating at first, but we can solve it using a clever substitution and the quadratic formula. Here's how:

1. Substitution

Let's simplify the equation by substituting a new variable. Let y = (x + 3)^2. This allows us to rewrite the equation as:

y^2 + 2y - 8 = 0

2. Quadratic Formula

Now we have a simple quadratic equation. We can solve for y using the quadratic formula:

y = (-b ± √(b^2 - 4ac)) / 2a

Where a = 1, b = 2, and c = -8. Plugging in the values, we get:

y = (-2 ± √(2^2 - 4 * 1 * -8)) / 2 * 1

y = (-2 ± √(36)) / 2

y = (-2 ± 6) / 2

This gives us two possible solutions for y:

y1 = 2

y2 = -4

3. Solving for x

Now we need to substitute back to find the values of x. Remember that y = (x + 3)^2.

For y1 = 2:

(x + 3)^2 = 2

  • Take the square root of both sides: x + 3 = ±√2
  • Isolate x: x = -3 ± √2

For y2 = -4:

(x + 3)^2 = -4

  • This equation has no real solutions because the square of a real number cannot be negative.

4. Solution

Therefore, the solutions to the original equation (x+3)^4 + 2(x+3)^2 - 8 = 0 are:

x = -3 + √2

x = -3 - √2

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