15=0.002(2x^2+10x+3000)

Solution for 15=0.002(2x^2+10x+3000) equation:

Simplifying
15 = 0.002(2x2 + 10x + 3000)

Reorder the terms:
15 = 0.002(3000 + 10x + 2x2)
15 = (3000 * 0.002 + 10x * 0.002 + 2x2 * 0.002)
15 = (6 + 0.02x + 0.004x2)

Solving
15 = 6 + 0.02x + 0.004x2

Solving for variable 'x'.

Combine like terms: 15 + -6 = 9
9 + -0.02x + -0.004x2 = 6 + 0.02x + 0.004x2 + -6 + -0.02x + -0.004x2

Reorder the terms:
9 + -0.02x + -0.004x2 = 6 + -6 + 0.02x + -0.02x + 0.004x2 + -0.004x2

Combine like terms: 6 + -6 = 0
9 + -0.02x + -0.004x2 = 0 + 0.02x + -0.02x + 0.004x2 + -0.004x2
9 + -0.02x + -0.004x2 = 0.02x + -0.02x + 0.004x2 + -0.004x2

Combine like terms: 0.02x + -0.02x = 0.00
9 + -0.02x + -0.004x2 = 0.00 + 0.004x2 + -0.004x2
9 + -0.02x + -0.004x2 = 0.004x2 + -0.004x2

Combine like terms: 0.004x2 + -0.004x2 = 0.000
9 + -0.02x + -0.004x2 = 0.000

Begin completing the square.  Divide all terms by
-0.004 the coefficient of the squared term: 

Divide each side by '-0.004'.
-2250 + 5x + x2 = 0

Move the constant term to the right:

Add '2250' to each side of the equation.
-2250 + 5x + 2250 + x2 = 0 + 2250

Reorder the terms:
-2250 + 2250 + 5x + x2 = 0 + 2250

Combine like terms: -2250 + 2250 = 0
0 + 5x + x2 = 0 + 2250
5x + x2 = 0 + 2250

Combine like terms: 0 + 2250 = 2250
5x + x2 = 2250

The x term is 5x.  Take half its coefficient (2.5).
Square it (6.25) and add it to both sides.

Add '6.25' to each side of the equation.
5x + 6.25 + x2 = 2250 + 6.25

Reorder the terms:
6.25 + 5x + x2 = 2250 + 6.25

Combine like terms: 2250 + 6.25 = 2256.25
6.25 + 5x + x2 = 2256.25

Factor a perfect square on the left side:
(x + 2.5)(x + 2.5) = 2256.25

Calculate the square root of the right side: 47.5

Break this problem into two subproblems by setting 
(x + 2.5) equal to 47.5 and -47.5.

Subproblem 1
x + 2.5 = 47.5

Simplifying
x + 2.5 = 47.5

Reorder the terms:
2.5 + x = 47.5

Solving
2.5 + x = 47.5

Solving for variable 'x'.

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

Add '-2.5' to each side of the equation.
2.5 + -2.5 + x = 47.5 + -2.5

Combine like terms: 2.5 + -2.5 = 0.0
0.0 + x = 47.5 + -2.5
x = 47.5 + -2.5

Combine like terms: 47.5 + -2.5 = 45
x = 45

Simplifying
x = 45

Subproblem 2
x + 2.5 = -47.5

Simplifying
x + 2.5 = -47.5

Reorder the terms:
2.5 + x = -47.5

Solving
2.5 + x = -47.5

Solving for variable 'x'.

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

Add '-2.5' to each side of the equation.
2.5 + -2.5 + x = -47.5 + -2.5

Combine like terms: 2.5 + -2.5 = 0.0
0.0 + x = -47.5 + -2.5
x = -47.5 + -2.5

Combine like terms: -47.5 + -2.5 = -50
x = -50

Simplifying
x = -50

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {45, -50}