15(x)=-4.9x^2+10x+40

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Solution for 15(x)=-4.9x^2+10x+40 equation:


Simplifying
15(x) = -4.9x2 + 10x + 40

Reorder the terms:
15x = 40 + 10x + -4.9x2

Solving
15x = 40 + 10x + -4.9x2

Solving for variable 'x'.

Reorder the terms:
-40 + 15x + -10x + 4.9x2 = 40 + 10x + -4.9x2 + -40 + -10x + 4.9x2

Combine like terms: 15x + -10x = 5x
-40 + 5x + 4.9x2 = 40 + 10x + -4.9x2 + -40 + -10x + 4.9x2

Reorder the terms:
-40 + 5x + 4.9x2 = 40 + -40 + 10x + -10x + -4.9x2 + 4.9x2

Combine like terms: 40 + -40 = 0
-40 + 5x + 4.9x2 = 0 + 10x + -10x + -4.9x2 + 4.9x2
-40 + 5x + 4.9x2 = 10x + -10x + -4.9x2 + 4.9x2

Combine like terms: 10x + -10x = 0
-40 + 5x + 4.9x2 = 0 + -4.9x2 + 4.9x2
-40 + 5x + 4.9x2 = -4.9x2 + 4.9x2

Combine like terms: -4.9x2 + 4.9x2 = 0.0
-40 + 5x + 4.9x2 = 0.0

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

Divide each side by '4.9'.
-8.163265306 + 1.020408163x + x2 = 0

Move the constant term to the right:

Add '8.163265306' to each side of the equation.
-8.163265306 + 1.020408163x + 8.163265306 + x2 = 0 + 8.163265306

Reorder the terms:
-8.163265306 + 8.163265306 + 1.020408163x + x2 = 0 + 8.163265306

Combine like terms: -8.163265306 + 8.163265306 = 0.000000000
0.000000000 + 1.020408163x + x2 = 0 + 8.163265306
1.020408163x + x2 = 0 + 8.163265306

Combine like terms: 0 + 8.163265306 = 8.163265306
1.020408163x + x2 = 8.163265306

The x term is 1.020408163x.  Take half its coefficient (0.5102040815).
Square it (0.2603082048) and add it to both sides.

Add '0.2603082048' to each side of the equation.
1.020408163x + 0.2603082048 + x2 = 8.163265306 + 0.2603082048

Reorder the terms:
0.2603082048 + 1.020408163x + x2 = 8.163265306 + 0.2603082048

Combine like terms: 8.163265306 + 0.2603082048 = 8.4235735108
0.2603082048 + 1.020408163x + x2 = 8.4235735108

Factor a perfect square on the left side:
(x + 0.5102040815)(x + 0.5102040815) = 8.4235735108

Calculate the square root of the right side: 2.902339317

Break this problem into two subproblems by setting 
(x + 0.5102040815) equal to 2.902339317 and -2.902339317.

Subproblem 1

x + 0.5102040815 = 2.902339317 Simplifying x + 0.5102040815 = 2.902339317 Reorder the terms: 0.5102040815 + x = 2.902339317 Solving 0.5102040815 + x = 2.902339317 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5102040815' to each side of the equation. 0.5102040815 + -0.5102040815 + x = 2.902339317 + -0.5102040815 Combine like terms: 0.5102040815 + -0.5102040815 = 0.0000000000 0.0000000000 + x = 2.902339317 + -0.5102040815 x = 2.902339317 + -0.5102040815 Combine like terms: 2.902339317 + -0.5102040815 = 2.3921352355 x = 2.3921352355 Simplifying x = 2.3921352355

Subproblem 2

x + 0.5102040815 = -2.902339317 Simplifying x + 0.5102040815 = -2.902339317 Reorder the terms: 0.5102040815 + x = -2.902339317 Solving 0.5102040815 + x = -2.902339317 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5102040815' to each side of the equation. 0.5102040815 + -0.5102040815 + x = -2.902339317 + -0.5102040815 Combine like terms: 0.5102040815 + -0.5102040815 = 0.0000000000 0.0000000000 + x = -2.902339317 + -0.5102040815 x = -2.902339317 + -0.5102040815 Combine like terms: -2.902339317 + -0.5102040815 = -3.4125433985 x = -3.4125433985 Simplifying x = -3.4125433985

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.3921352355, -3.4125433985}

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