-15=2x^2+4x

Solution for -15=2x^2+4x equation:

Simplifying
-15 = 2x2 + 4x

Reorder the terms:
-15 = 4x + 2x2

Solving
-15 = 4x + 2x2

Solving for variable 'x'.

Reorder the terms:
-15 + -4x + -2x2 = 4x + -4x + 2x2 + -2x2

Combine like terms: 4x + -4x = 0
-15 + -4x + -2x2 = 0 + 2x2 + -2x2
-15 + -4x + -2x2 = 2x2 + -2x2

Combine like terms: 2x2 + -2x2 = 0
-15 + -4x + -2x2 = 0

Factor out the Greatest Common Factor (GCF), '-1'.
-1(15 + 4x + 2x2) = 0

Ignore the factor -1.
Subproblem 1
Set the factor '(15 + 4x + 2x2)' equal to zero and attempt to solve:

Simplifying
15 + 4x + 2x2 = 0

Solving
15 + 4x + 2x2 = 0

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

Divide each side by '2'.
7.5 + 2x + x2 = 0

Move the constant term to the right:

Add '-7.5' to each side of the equation.
7.5 + 2x + -7.5 + x2 = 0 + -7.5

Reorder the terms:
7.5 + -7.5 + 2x + x2 = 0 + -7.5

Combine like terms: 7.5 + -7.5 = 0.0
0.0 + 2x + x2 = 0 + -7.5
2x + x2 = 0 + -7.5

Combine like terms: 0 + -7.5 = -7.5
2x + x2 = -7.5

The x term is 2x.  Take half its coefficient (1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
2x + 1 + x2 = -7.5 + 1

Reorder the terms:
1 + 2x + x2 = -7.5 + 1

Combine like terms: -7.5 + 1 = -6.5
1 + 2x + x2 = -6.5

Factor a perfect square on the left side:
(x + 1)(x + 1) = -6.5

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.