8X^2+20X-11=0

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Solution for 8X^2+20X-11=0 equation:


Simplifying
8X2 + 20X + -11 = 0

Reorder the terms:
-11 + 20X + 8X2 = 0

Solving
-11 + 20X + 8X2 = 0

Solving for variable 'X'.

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

Divide each side by '8'.
-1.375 + 2.5X + X2 = 0

Move the constant term to the right:

Add '1.375' to each side of the equation.
-1.375 + 2.5X + 1.375 + X2 = 0 + 1.375

Reorder the terms:
-1.375 + 1.375 + 2.5X + X2 = 0 + 1.375

Combine like terms: -1.375 + 1.375 = 0.000
0.000 + 2.5X + X2 = 0 + 1.375
2.5X + X2 = 0 + 1.375

Combine like terms: 0 + 1.375 = 1.375
2.5X + X2 = 1.375

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 = 1.375 + 1.5625

Reorder the terms:
1.5625 + 2.5X + X2 = 1.375 + 1.5625

Combine like terms: 1.375 + 1.5625 = 2.9375
1.5625 + 2.5X + X2 = 2.9375

Factor a perfect square on the left side:
(X + 1.25)(X + 1.25) = 2.9375

Calculate the square root of the right side: 1.71391365

Break this problem into two subproblems by setting 
(X + 1.25) equal to 1.71391365 and -1.71391365.

Subproblem 1

X + 1.25 = 1.71391365 Simplifying X + 1.25 = 1.71391365 Reorder the terms: 1.25 + X = 1.71391365 Solving 1.25 + X = 1.71391365 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 = 1.71391365 + -1.25 Combine like terms: 1.25 + -1.25 = 0.00 0.00 + X = 1.71391365 + -1.25 X = 1.71391365 + -1.25 Combine like terms: 1.71391365 + -1.25 = 0.46391365 X = 0.46391365 Simplifying X = 0.46391365

Subproblem 2

X + 1.25 = -1.71391365 Simplifying X + 1.25 = -1.71391365 Reorder the terms: 1.25 + X = -1.71391365 Solving 1.25 + X = -1.71391365 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 = -1.71391365 + -1.25 Combine like terms: 1.25 + -1.25 = 0.00 0.00 + X = -1.71391365 + -1.25 X = -1.71391365 + -1.25 Combine like terms: -1.71391365 + -1.25 = -2.96391365 X = -2.96391365 Simplifying X = -2.96391365

Solution

The solution to the problem is based on the solutions from the subproblems. X = {0.46391365, -2.96391365}

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