5=15x^2+42x

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Solution for 5=15x^2+42x equation:


Simplifying
5 = 15x2 + 42x

Reorder the terms:
5 = 42x + 15x2

Solving
5 = 42x + 15x2

Solving for variable 'x'.

Reorder the terms:
5 + -42x + -15x2 = 42x + -42x + 15x2 + -15x2

Combine like terms: 42x + -42x = 0
5 + -42x + -15x2 = 0 + 15x2 + -15x2
5 + -42x + -15x2 = 15x2 + -15x2

Combine like terms: 15x2 + -15x2 = 0
5 + -42x + -15x2 = 0

Begin completing the square.  Divide all terms by
-15 the coefficient of the squared term: 

Divide each side by '-15'.
-0.3333333333 + 2.8x + x2 = 0

Move the constant term to the right:

Add '0.3333333333' to each side of the equation.
-0.3333333333 + 2.8x + 0.3333333333 + x2 = 0 + 0.3333333333

Reorder the terms:
-0.3333333333 + 0.3333333333 + 2.8x + x2 = 0 + 0.3333333333

Combine like terms: -0.3333333333 + 0.3333333333 = 0.0000000000
0.0000000000 + 2.8x + x2 = 0 + 0.3333333333
2.8x + x2 = 0 + 0.3333333333

Combine like terms: 0 + 0.3333333333 = 0.3333333333
2.8x + x2 = 0.3333333333

The x term is 2.8x.  Take half its coefficient (1.4).
Square it (1.96) and add it to both sides.

Add '1.96' to each side of the equation.
2.8x + 1.96 + x2 = 0.3333333333 + 1.96

Reorder the terms:
1.96 + 2.8x + x2 = 0.3333333333 + 1.96

Combine like terms: 0.3333333333 + 1.96 = 2.2933333333
1.96 + 2.8x + x2 = 2.2933333333

Factor a perfect square on the left side:
(x + 1.4)(x + 1.4) = 2.2933333333

Calculate the square root of the right side: 1.514375559

Break this problem into two subproblems by setting 
(x + 1.4) equal to 1.514375559 and -1.514375559.

Subproblem 1

x + 1.4 = 1.514375559 Simplifying x + 1.4 = 1.514375559 Reorder the terms: 1.4 + x = 1.514375559 Solving 1.4 + x = 1.514375559 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.4' to each side of the equation. 1.4 + -1.4 + x = 1.514375559 + -1.4 Combine like terms: 1.4 + -1.4 = 0.0 0.0 + x = 1.514375559 + -1.4 x = 1.514375559 + -1.4 Combine like terms: 1.514375559 + -1.4 = 0.114375559 x = 0.114375559 Simplifying x = 0.114375559

Subproblem 2

x + 1.4 = -1.514375559 Simplifying x + 1.4 = -1.514375559 Reorder the terms: 1.4 + x = -1.514375559 Solving 1.4 + x = -1.514375559 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.4' to each side of the equation. 1.4 + -1.4 + x = -1.514375559 + -1.4 Combine like terms: 1.4 + -1.4 = 0.0 0.0 + x = -1.514375559 + -1.4 x = -1.514375559 + -1.4 Combine like terms: -1.514375559 + -1.4 = -2.914375559 x = -2.914375559 Simplifying x = -2.914375559

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.114375559, -2.914375559}

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