-5a(a-1)-(4a+8)=

Solution for -5a(a-1)-(4a+8)= equation:

Simplifying
-5a(a + -1) + -1(4a + 8) = 0

Reorder the terms:
-5a(-1 + a) + -1(4a + 8) = 0
(-1 * -5a + a * -5a) + -1(4a + 8) = 0
(5a + -5a2) + -1(4a + 8) = 0

Reorder the terms:
5a + -5a2 + -1(8 + 4a) = 0
5a + -5a2 + (8 * -1 + 4a * -1) = 0
5a + -5a2 + (-8 + -4a) = 0

Reorder the terms:
-8 + 5a + -4a + -5a2 = 0

Combine like terms: 5a + -4a = 1a
-8 + 1a + -5a2 = 0

Solving
-8 + 1a + -5a2 = 0

Solving for variable 'a'.

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

Divide each side by '-5'.
1.6 + -0.2a + a2 = 0

Move the constant term to the right:

Add '-1.6' to each side of the equation.
1.6 + -0.2a + -1.6 + a2 = 0 + -1.6

Reorder the terms:
1.6 + -1.6 + -0.2a + a2 = 0 + -1.6

Combine like terms: 1.6 + -1.6 = 0.0
0.0 + -0.2a + a2 = 0 + -1.6
-0.2a + a2 = 0 + -1.6

Combine like terms: 0 + -1.6 = -1.6
-0.2a + a2 = -1.6

The a term is -0.2a.  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.
-0.2a + 0.01 + a2 = -1.6 + 0.01

Reorder the terms:
0.01 + -0.2a + a2 = -1.6 + 0.01

Combine like terms: -1.6 + 0.01 = -1.59
0.01 + -0.2a + a2 = -1.59

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

Can't calculate square root of the right side.

The solution to this equation could not be determined.