Find all complex zeros for the following function.

Question

Find all complex zeros for the following function.

h(x) = x^4+20x²-125

Answer 1

Take the equation, substitute y = x^2 into it to reduce it to y^2 + 20y -125 = 0

You find y = 5 & -25

So, x^2 = 5 & -25 the 5 yields real roots +-5^(1/2)

but the -25 yields =- (-25)^(1/2) which yields +- 5i (2 complex roots)