3x(x-5)-3x*3x=-30

Solution for 3x(x-5)-3x*3x=-30 equation:

Simplifying
3x(x + -5) + -3x * 3x = -30

Reorder the terms:
3x(-5 + x) + -3x * 3x = -30
(-5 * 3x + x * 3x) + -3x * 3x = -30
(-15x + 3x2) + -3x * 3x = -30

Reorder the terms for easier multiplication:
-15x + 3x2 + -3 * 3x * x = -30

Multiply -3 * 3
-15x + 3x2 + -9x * x = -30

Multiply x * x
-15x + 3x2 + -9x2 = -30

Combine like terms: 3x2 + -9x2 = -6x2
-15x + -6x2 = -30

Solving
-15x + -6x2 = -30

Solving for variable 'x'.

Reorder the terms:
30 + -15x + -6x2 = -30 + 30

Combine like terms: -30 + 30 = 0
30 + -15x + -6x2 = 0

Factor out the Greatest Common Factor (GCF), '3'.
3(10 + -5x + -2x2) = 0

Ignore the factor 3.
Subproblem 1
Set the factor '(10 + -5x + -2x2)' equal to zero and attempt to solve:

Simplifying
10 + -5x + -2x2 = 0

Solving
10 + -5x + -2x2 = 0

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

Divide each side by '-2'.
-5 + 2.5x + x2 = 0

Move the constant term to the right:

Add '5' to each side of the equation.
-5 + 2.5x + 5 + x2 = 0 + 5

Reorder the terms:
-5 + 5 + 2.5x + x2 = 0 + 5

Combine like terms: -5 + 5 = 0
0 + 2.5x + x2 = 0 + 5
2.5x + x2 = 0 + 5

Combine like terms: 0 + 5 = 5
2.5x + x2 = 5

The x term is 2.5x.  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.
2.5x + 1.5625 + x2 = 5 + 1.5625

Reorder the terms:
1.5625 + 2.5x + x2 = 5 + 1.5625

Combine like terms: 5 + 1.5625 = 6.5625
1.5625 + 2.5x + x2 = 6.5625

Factor a perfect square on the left side:
(x + 1.25)(x + 1.25) = 6.5625

Calculate the square root of the right side: 2.561737691

Break this problem into two subproblems by setting 
(x + 1.25) equal to 2.561737691 and -2.561737691.

Subproblem 1
x + 1.25 = 2.561737691

Simplifying
x + 1.25 = 2.561737691

Reorder the terms:
1.25 + x = 2.561737691

Solving
1.25 + x = 2.561737691

Solving for variable 'x'.

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

Add '-1.25' to each side of the equation.
1.25 + -1.25 + x = 2.561737691 + -1.25

Combine like terms: 1.25 + -1.25 = 0.00
0.00 + x = 2.561737691 + -1.25
x = 2.561737691 + -1.25

Combine like terms: 2.561737691 + -1.25 = 1.311737691
x = 1.311737691

Simplifying
x = 1.311737691

Subproblem 2
x + 1.25 = -2.561737691

Simplifying
x + 1.25 = -2.561737691

Reorder the terms:
1.25 + x = -2.561737691

Solving
1.25 + x = -2.561737691

Solving for variable 'x'.

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

Add '-1.25' to each side of the equation.
1.25 + -1.25 + x = -2.561737691 + -1.25

Combine like terms: 1.25 + -1.25 = 0.00
0.00 + x = -2.561737691 + -1.25
x = -2.561737691 + -1.25

Combine like terms: -2.561737691 + -1.25 = -3.811737691
x = -3.811737691

Simplifying
x = -3.811737691

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {1.311737691, -3.811737691}
Solution
x = {1.311737691, -3.811737691}