Use factoring to find zeros

Question

Use factoring to find all zeros of x^4 +2x^2-8=0. 

- Simplify radicals.

- Enter zero separated by commas.

- Enter exact values, not decimal approximations. 

- Use I for imaginary numbers.

Answer 1

Solve by substitution, so you can work with a quadratic equation.

 

u = x²

 

u² + 2u - 8 = (u + 4)(u - 2) = 0

 

u = -4 or 2

 

x² = -4 or 2

 

x = ±2i or ±√2