Answer:
1.  1/2 +/-√5
2.  1 +/-  i √6/2.
Step-by-step explanation:
1. Â f(x) = 4x^2 - 8x - 1
x = [-(-8) +/-√((-8)^2 - 4*4*-1)] / (2*4)
x =[ 8 +/- √80] / 8
= 1 +/- 4√5/8
= 1 +/- √5/2
= 1/2 +/-√5
2. By a similar method the zeros of the the second equation are:
x = [-(-4) +/- √((-4)^2 - 4*2*5)]  / 4
= 4 +/- √(16 - 40) / 4
= 1 +/- √(-24)/4
= 1 +/- i  √6 * 2 / 4
= 1 +/-  i √6/2.