16x^2-15x-21=0

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Solution for 16x^2-15x-21=0 equation:


Simplifying
16x2 + -15x + -21 = 0

Reorder the terms:
-21 + -15x + 16x2 = 0

Solving
-21 + -15x + 16x2 = 0

Solving for variable 'x'.

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

Divide each side by '16'.
-1.3125 + -0.9375x + x2 = 0

Move the constant term to the right:

Add '1.3125' to each side of the equation.
-1.3125 + -0.9375x + 1.3125 + x2 = 0 + 1.3125

Reorder the terms:
-1.3125 + 1.3125 + -0.9375x + x2 = 0 + 1.3125

Combine like terms: -1.3125 + 1.3125 = 0.0000
0.0000 + -0.9375x + x2 = 0 + 1.3125
-0.9375x + x2 = 0 + 1.3125

Combine like terms: 0 + 1.3125 = 1.3125
-0.9375x + x2 = 1.3125

The x term is -0.9375x.  Take half its coefficient (-0.46875).
Square it (0.2197265625) and add it to both sides.

Add '0.2197265625' to each side of the equation.
-0.9375x + 0.2197265625 + x2 = 1.3125 + 0.2197265625

Reorder the terms:
0.2197265625 + -0.9375x + x2 = 1.3125 + 0.2197265625

Combine like terms: 1.3125 + 0.2197265625 = 1.5322265625
0.2197265625 + -0.9375x + x2 = 1.5322265625

Factor a perfect square on the left side:
(x + -0.46875)(x + -0.46875) = 1.5322265625

Calculate the square root of the right side: 1.237831395

Break this problem into two subproblems by setting 
(x + -0.46875) equal to 1.237831395 and -1.237831395.

Subproblem 1

x + -0.46875 = 1.237831395 Simplifying x + -0.46875 = 1.237831395 Reorder the terms: -0.46875 + x = 1.237831395 Solving -0.46875 + x = 1.237831395 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.46875' to each side of the equation. -0.46875 + 0.46875 + x = 1.237831395 + 0.46875 Combine like terms: -0.46875 + 0.46875 = 0.00000 0.00000 + x = 1.237831395 + 0.46875 x = 1.237831395 + 0.46875 Combine like terms: 1.237831395 + 0.46875 = 1.706581395 x = 1.706581395 Simplifying x = 1.706581395

Subproblem 2

x + -0.46875 = -1.237831395 Simplifying x + -0.46875 = -1.237831395 Reorder the terms: -0.46875 + x = -1.237831395 Solving -0.46875 + x = -1.237831395 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.46875' to each side of the equation. -0.46875 + 0.46875 + x = -1.237831395 + 0.46875 Combine like terms: -0.46875 + 0.46875 = 0.00000 0.00000 + x = -1.237831395 + 0.46875 x = -1.237831395 + 0.46875 Combine like terms: -1.237831395 + 0.46875 = -0.769081395 x = -0.769081395 Simplifying x = -0.769081395

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.706581395, -0.769081395}

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