-(-5z^2+z-8)=0

Solution for -(-5z^2+z-8)=0 equation:

Simplifying
-1(-5z2 + z + -8) = 0

Reorder the terms:
-1(-8 + z + -5z2) = 0
(-8 * -1 + z * -1 + -5z2 * -1) = 0
(8 + -1z + 5z2) = 0

Solving
8 + -1z + 5z2 = 0

Solving for variable 'z'.

Begin completing the square.  Divide all terms by
5 the coefficient of the squared term: 

Divide each side by '5'.
1.6 + -0.2z + z2 = 0

Move the constant term to the right:

Add '-1.6' to each side of the equation.
1.6 + -0.2z + -1.6 + z2 = 0 + -1.6

Reorder the terms:
1.6 + -1.6 + -0.2z + z2 = 0 + -1.6

Combine like terms: 1.6 + -1.6 = 0.0
0.0 + -0.2z + z2 = 0 + -1.6
-0.2z + z2 = 0 + -1.6

Combine like terms: 0 + -1.6 = -1.6
-0.2z + z2 = -1.6

The z term is -0.2z.  Take half its coefficient (-0.1).
Square it (0.01) and add it to both sides.

Add '0.01' to each side of the equation.
-0.2z + 0.01 + z2 = -1.6 + 0.01

Reorder the terms:
0.01 + -0.2z + z2 = -1.6 + 0.01

Combine like terms: -1.6 + 0.01 = -1.59
0.01 + -0.2z + z2 = -1.59

Factor a perfect square on the left side:
(z + -0.1)(z + -0.1) = -1.59

Can't calculate square root of the right side.

The solution to this equation could not be determined.