If it's not what You are looking for type in the equation solver your own equation and let us solve it.
D( z )
z = 0
z = 0
z = 0
z in (-oo:0) U (0:+oo)
2*z-(5/z)-8 = 0
2*z-5*z^-1-8 = 0
2*z^1-5*z^-1-8*z^0 = 0
(2*z^2-8*z^1-5*z^0)/(z^1) = 0 // * z^2
z^1*(2*z^2-8*z^1-5*z^0) = 0
z^1
2*z^2-8*z-5 = 0
2*z^2-8*z-5 = 0
DELTA = (-8)^2-(-5*2*4)
DELTA = 104
DELTA > 0
z = (104^(1/2)+8)/(2*2) or z = (8-104^(1/2))/(2*2)
z = (2*26^(1/2)+8)/4 or z = (8-2*26^(1/2))/4
z in { (8-2*26^(1/2))/4, (2*26^(1/2)+8)/4}
z in { (8-2*26^(1/2))/4, (2*26^(1/2)+8)/4 }
| 9-4/8 | | 0.9x+0.3=5.7 | | 19-16=x/5 | | 22x-24x=5-7 | | -49+25=-3x+11x | | 8X-1=43x-1 | | 6-6=15x+14x | | 24/10=36/x | | 8X-1=4x-1 | | -36+16a=-3a^2-1 | | -1.5=-0.9u+0.4u | | (30x)+(40x)= | | 8/5t=-7/8 | | 8x-14=4x+3 | | 4z=1.5+2.9 | | 5m=3n+1 | | 6/7m-1/2=2/3 | | 4w-16w=60 | | 2/5x=2/9 | | -4r=5+-25 | | 0.5c=16 | | 4x(x-6)=(3x+4)(x-6) | | 0.5x=-15 | | 0.5m=-55 | | 15x-14y=1 | | 10x-7y=3 | | 1.04g-4=0.68 | | 2z-3=z+4 | | 48+5y-3=15y-11-2y | | -2(r+4)=35 | | -7x-1/3=7/4x-1/4 | | -21+17=-3x+5x |