4x^2+21x+25=0

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Solution for 4x^2+21x+25=0 equation:


Simplifying
4x2 + 21x + 25 = 0

Reorder the terms:
25 + 21x + 4x2 = 0

Solving
25 + 21x + 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'.
6.25 + 5.25x + x2 = 0

Move the constant term to the right:

Add '-6.25' to each side of the equation.
6.25 + 5.25x + -6.25 + x2 = 0 + -6.25

Reorder the terms:
6.25 + -6.25 + 5.25x + x2 = 0 + -6.25

Combine like terms: 6.25 + -6.25 = 0.00
0.00 + 5.25x + x2 = 0 + -6.25
5.25x + x2 = 0 + -6.25

Combine like terms: 0 + -6.25 = -6.25
5.25x + x2 = -6.25

The x term is 5.25x.  Take half its coefficient (2.625).
Square it (6.890625) and add it to both sides.

Add '6.890625' to each side of the equation.
5.25x + 6.890625 + x2 = -6.25 + 6.890625

Reorder the terms:
6.890625 + 5.25x + x2 = -6.25 + 6.890625

Combine like terms: -6.25 + 6.890625 = 0.640625
6.890625 + 5.25x + x2 = 0.640625

Factor a perfect square on the left side:
(x + 2.625)(x + 2.625) = 0.640625

Calculate the square root of the right side: 0.80039053

Break this problem into two subproblems by setting 
(x + 2.625) equal to 0.80039053 and -0.80039053.

Subproblem 1

x + 2.625 = 0.80039053 Simplifying x + 2.625 = 0.80039053 Reorder the terms: 2.625 + x = 0.80039053 Solving 2.625 + x = 0.80039053 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-2.625' to each side of the equation. 2.625 + -2.625 + x = 0.80039053 + -2.625 Combine like terms: 2.625 + -2.625 = 0.000 0.000 + x = 0.80039053 + -2.625 x = 0.80039053 + -2.625 Combine like terms: 0.80039053 + -2.625 = -1.82460947 x = -1.82460947 Simplifying x = -1.82460947

Subproblem 2

x + 2.625 = -0.80039053 Simplifying x + 2.625 = -0.80039053 Reorder the terms: 2.625 + x = -0.80039053 Solving 2.625 + x = -0.80039053 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-2.625' to each side of the equation. 2.625 + -2.625 + x = -0.80039053 + -2.625 Combine like terms: 2.625 + -2.625 = 0.000 0.000 + x = -0.80039053 + -2.625 x = -0.80039053 + -2.625 Combine like terms: -0.80039053 + -2.625 = -3.42539053 x = -3.42539053 Simplifying x = -3.42539053

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-1.82460947, -3.42539053}

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