40x^3+5x^2+15x=

Solution for 40x^3+5x^2+15x= equation:

Simplifying
40x3 + 5x2 + 15x = 0

Reorder the terms:
15x + 5x2 + 40x3 = 0

Solving
15x + 5x2 + 40x3 = 0

Solving for variable 'x'.

Factor out the Greatest Common Factor (GCF), '5x'.
5x(3 + x + 8x2) = 0

Ignore the factor 5.
Subproblem 1
Set the factor 'x' equal to zero and attempt to solve:

Simplifying
x = 0

Solving
x = 0

Move all terms containing x to the left, all other terms to the right.

Simplifying
x = 0
Subproblem 2
Set the factor '(3 + x + 8x2)' equal to zero and attempt to solve:

Simplifying
3 + x + 8x2 = 0

Solving
3 + x + 8x2 = 0

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

Divide each side by '8'.
0.375 + 0.125x + x2 = 0

Move the constant term to the right:

Add '-0.375' to each side of the equation.
0.375 + 0.125x + -0.375 + x2 = 0 + -0.375

Reorder the terms:
0.375 + -0.375 + 0.125x + x2 = 0 + -0.375

Combine like terms: 0.375 + -0.375 = 0.000
0.000 + 0.125x + x2 = 0 + -0.375
0.125x + x2 = 0 + -0.375

Combine like terms: 0 + -0.375 = -0.375
0.125x + x2 = -0.375

The x term is x.  Take half its coefficient (0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
0.125x + 0.25 + x2 = -0.375 + 0.25

Reorder the terms:
0.25 + 0.125x + x2 = -0.375 + 0.25

Combine like terms: -0.375 + 0.25 = -0.125
0.25 + 0.125x + x2 = -0.125

Factor a perfect square on the left side:
(x + 0.5)(x + 0.5) = -0.125

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.
Solution
x = {0}