4x^2+15x-100=0

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Solution for 4x^2+15x-100=0 equation:


Simplifying
4x2 + 15x + -100 = 0

Reorder the terms:
-100 + 15x + 4x2 = 0

Solving
-100 + 15x + 4x2 = 0

Solving for variable 'x'.

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

Divide each side by '4'.
-25 + 3.75x + x2 = 0

Move the constant term to the right:

Add '25' to each side of the equation.
-25 + 3.75x + 25 + x2 = 0 + 25

Reorder the terms:
-25 + 25 + 3.75x + x2 = 0 + 25

Combine like terms: -25 + 25 = 0
0 + 3.75x + x2 = 0 + 25
3.75x + x2 = 0 + 25

Combine like terms: 0 + 25 = 25
3.75x + x2 = 25

The x term is 3.75x.  Take half its coefficient (1.875).
Square it (3.515625) and add it to both sides.

Add '3.515625' to each side of the equation.
3.75x + 3.515625 + x2 = 25 + 3.515625

Reorder the terms:
3.515625 + 3.75x + x2 = 25 + 3.515625

Combine like terms: 25 + 3.515625 = 28.515625
3.515625 + 3.75x + x2 = 28.515625

Factor a perfect square on the left side:
(x + 1.875)(x + 1.875) = 28.515625

Calculate the square root of the right side: 5.340002341

Break this problem into two subproblems by setting 
(x + 1.875) equal to 5.340002341 and -5.340002341.

Subproblem 1

x + 1.875 = 5.340002341 Simplifying x + 1.875 = 5.340002341 Reorder the terms: 1.875 + x = 5.340002341 Solving 1.875 + x = 5.340002341 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.875' to each side of the equation. 1.875 + -1.875 + x = 5.340002341 + -1.875 Combine like terms: 1.875 + -1.875 = 0.000 0.000 + x = 5.340002341 + -1.875 x = 5.340002341 + -1.875 Combine like terms: 5.340002341 + -1.875 = 3.465002341 x = 3.465002341 Simplifying x = 3.465002341

Subproblem 2

x + 1.875 = -5.340002341 Simplifying x + 1.875 = -5.340002341 Reorder the terms: 1.875 + x = -5.340002341 Solving 1.875 + x = -5.340002341 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.875' to each side of the equation. 1.875 + -1.875 + x = -5.340002341 + -1.875 Combine like terms: 1.875 + -1.875 = 0.000 0.000 + x = -5.340002341 + -1.875 x = -5.340002341 + -1.875 Combine like terms: -5.340002341 + -1.875 = -7.215002341 x = -7.215002341 Simplifying x = -7.215002341

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.465002341, -7.215002341}

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