-2d(2d+5)=10

Solution for -2d(2d+5)=10 equation:

Simplifying
-2d(2d + 5) = 10

Reorder the terms:
-2d(5 + 2d) = 10
(5 * -2d + 2d * -2d) = 10
(-10d + -4d2) = 10

Solving
-10d + -4d2 = 10

Solving for variable 'd'.

Reorder the terms:
-10 + -10d + -4d2 = 10 + -10

Combine like terms: 10 + -10 = 0
-10 + -10d + -4d2 = 0

Factor out the Greatest Common Factor (GCF), '-2'.
-2(5 + 5d + 2d2) = 0

Ignore the factor -2.
Subproblem 1
Set the factor '(5 + 5d + 2d2)' equal to zero and attempt to solve:

Simplifying
5 + 5d + 2d2 = 0

Solving
5 + 5d + 2d2 = 0

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

Divide each side by '2'.
2.5 + 2.5d + d2 = 0

Move the constant term to the right:

Add '-2.5' to each side of the equation.
2.5 + 2.5d + -2.5 + d2 = 0 + -2.5

Reorder the terms:
2.5 + -2.5 + 2.5d + d2 = 0 + -2.5

Combine like terms: 2.5 + -2.5 = 0.0
0.0 + 2.5d + d2 = 0 + -2.5
2.5d + d2 = 0 + -2.5

Combine like terms: 0 + -2.5 = -2.5
2.5d + d2 = -2.5

The d term is 2.5d.  Take half its coefficient (1.25).
Square it (1.5625) and add it to both sides.

Add '1.5625' to each side of the equation.
2.5d + 1.5625 + d2 = -2.5 + 1.5625

Reorder the terms:
1.5625 + 2.5d + d2 = -2.5 + 1.5625

Combine like terms: -2.5 + 1.5625 = -0.9375
1.5625 + 2.5d + d2 = -0.9375

Factor a perfect square on the left side:
(d + 1.25)(d + 1.25) = -0.9375

Can't calculate square root of the right side.

The solution to this equation could not be determined.

This subproblem is being ignored because a solution could not be determined.

The solution to this equation could not be determined.