Question

show that the polynomial x^4+4x^2+5 has no zeros

Answer 1

x^4+4x^2-5
=(x^2)^2+4x^2-5 Let,x^2=y
=y^2+4y-5
=(y+5)(y-1)
y=-5
x^2=-5
y=1
x^2=1
x=1
x not is to 0(zero).
Proved