Hello from MrBillDoesMath!
Answer:
Solutions: x = +\- 5i or x = +\- sqrt(5)
Discussion:
Factor x^4 - 25:
x^4 - 25 = (x^2+5) (x^2-5) => factor x^2 - 5
x^4 - 25 = (x^2+5)(x + sqrt(5)) (x - sqrt(5)) => factor x^2 + 5
x^4 = 25 = (x +5i)(x-5i) (x + sqrt(5)) (x - sqrt(5))
Hence the solutions are
x = +\- 5i and x = +\- sqrt(5)
Thank you,
MrB