7x^2+9x-4=0

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Solution for 7x^2+9x-4=0 equation:


Simplifying
7x2 + 9x + -4 = 0

Reorder the terms:
-4 + 9x + 7x2 = 0

Solving
-4 + 9x + 7x2 = 0

Solving for variable 'x'.

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

Divide each side by '7'.
-0.5714285714 + 1.285714286x + x2 = 0

Move the constant term to the right:

Add '0.5714285714' to each side of the equation.
-0.5714285714 + 1.285714286x + 0.5714285714 + x2 = 0 + 0.5714285714

Reorder the terms:
-0.5714285714 + 0.5714285714 + 1.285714286x + x2 = 0 + 0.5714285714

Combine like terms: -0.5714285714 + 0.5714285714 = 0.0000000000
0.0000000000 + 1.285714286x + x2 = 0 + 0.5714285714
1.285714286x + x2 = 0 + 0.5714285714

Combine like terms: 0 + 0.5714285714 = 0.5714285714
1.285714286x + x2 = 0.5714285714

The x term is 1.285714286x.  Take half its coefficient (0.642857143).
Square it (0.4132653063) and add it to both sides.

Add '0.4132653063' to each side of the equation.
1.285714286x + 0.4132653063 + x2 = 0.5714285714 + 0.4132653063

Reorder the terms:
0.4132653063 + 1.285714286x + x2 = 0.5714285714 + 0.4132653063

Combine like terms: 0.5714285714 + 0.4132653063 = 0.9846938777
0.4132653063 + 1.285714286x + x2 = 0.9846938777

Factor a perfect square on the left side:
(x + 0.642857143)(x + 0.642857143) = 0.9846938777

Calculate the square root of the right side: 0.992317428

Break this problem into two subproblems by setting 
(x + 0.642857143) equal to 0.992317428 and -0.992317428.

Subproblem 1

x + 0.642857143 = 0.992317428 Simplifying x + 0.642857143 = 0.992317428 Reorder the terms: 0.642857143 + x = 0.992317428 Solving 0.642857143 + x = 0.992317428 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.642857143' to each side of the equation. 0.642857143 + -0.642857143 + x = 0.992317428 + -0.642857143 Combine like terms: 0.642857143 + -0.642857143 = 0.000000000 0.000000000 + x = 0.992317428 + -0.642857143 x = 0.992317428 + -0.642857143 Combine like terms: 0.992317428 + -0.642857143 = 0.349460285 x = 0.349460285 Simplifying x = 0.349460285

Subproblem 2

x + 0.642857143 = -0.992317428 Simplifying x + 0.642857143 = -0.992317428 Reorder the terms: 0.642857143 + x = -0.992317428 Solving 0.642857143 + x = -0.992317428 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.642857143' to each side of the equation. 0.642857143 + -0.642857143 + x = -0.992317428 + -0.642857143 Combine like terms: 0.642857143 + -0.642857143 = 0.000000000 0.000000000 + x = -0.992317428 + -0.642857143 x = -0.992317428 + -0.642857143 Combine like terms: -0.992317428 + -0.642857143 = -1.635174571 x = -1.635174571 Simplifying x = -1.635174571

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.349460285, -1.635174571}

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