15=5x^2-7x+4

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Solution for 15=5x^2-7x+4 equation:


Simplifying
15 = 5x2 + -7x + 4

Reorder the terms:
15 = 4 + -7x + 5x2

Solving
15 = 4 + -7x + 5x2

Solving for variable 'x'.

Combine like terms: 15 + -4 = 11
11 + 7x + -5x2 = 4 + -7x + 5x2 + -4 + 7x + -5x2

Reorder the terms:
11 + 7x + -5x2 = 4 + -4 + -7x + 7x + 5x2 + -5x2

Combine like terms: 4 + -4 = 0
11 + 7x + -5x2 = 0 + -7x + 7x + 5x2 + -5x2
11 + 7x + -5x2 = -7x + 7x + 5x2 + -5x2

Combine like terms: -7x + 7x = 0
11 + 7x + -5x2 = 0 + 5x2 + -5x2
11 + 7x + -5x2 = 5x2 + -5x2

Combine like terms: 5x2 + -5x2 = 0
11 + 7x + -5x2 = 0

Begin completing the square.  Divide all terms by
-5 the coefficient of the squared term: 

Divide each side by '-5'.
-2.2 + -1.4x + x2 = 0

Move the constant term to the right:

Add '2.2' to each side of the equation.
-2.2 + -1.4x + 2.2 + x2 = 0 + 2.2

Reorder the terms:
-2.2 + 2.2 + -1.4x + x2 = 0 + 2.2

Combine like terms: -2.2 + 2.2 = 0.0
0.0 + -1.4x + x2 = 0 + 2.2
-1.4x + x2 = 0 + 2.2

Combine like terms: 0 + 2.2 = 2.2
-1.4x + x2 = 2.2

The x term is -1.4x.  Take half its coefficient (-0.7).
Square it (0.49) and add it to both sides.

Add '0.49' to each side of the equation.
-1.4x + 0.49 + x2 = 2.2 + 0.49

Reorder the terms:
0.49 + -1.4x + x2 = 2.2 + 0.49

Combine like terms: 2.2 + 0.49 = 2.69
0.49 + -1.4x + x2 = 2.69

Factor a perfect square on the left side:
(x + -0.7)(x + -0.7) = 2.69

Calculate the square root of the right side: 1.640121947

Break this problem into two subproblems by setting 
(x + -0.7) equal to 1.640121947 and -1.640121947.

Subproblem 1

x + -0.7 = 1.640121947 Simplifying x + -0.7 = 1.640121947 Reorder the terms: -0.7 + x = 1.640121947 Solving -0.7 + x = 1.640121947 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.7' to each side of the equation. -0.7 + 0.7 + x = 1.640121947 + 0.7 Combine like terms: -0.7 + 0.7 = 0.0 0.0 + x = 1.640121947 + 0.7 x = 1.640121947 + 0.7 Combine like terms: 1.640121947 + 0.7 = 2.340121947 x = 2.340121947 Simplifying x = 2.340121947

Subproblem 2

x + -0.7 = -1.640121947 Simplifying x + -0.7 = -1.640121947 Reorder the terms: -0.7 + x = -1.640121947 Solving -0.7 + x = -1.640121947 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.7' to each side of the equation. -0.7 + 0.7 + x = -1.640121947 + 0.7 Combine like terms: -0.7 + 0.7 = 0.0 0.0 + x = -1.640121947 + 0.7 x = -1.640121947 + 0.7 Combine like terms: -1.640121947 + 0.7 = -0.940121947 x = -0.940121947 Simplifying x = -0.940121947

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.340121947, -0.940121947}

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