2x^2+4x-81=0

Simple and best practice solution for 2x^2+4x-81=0 equation. Check how easy it is, and learn it for the future. Our solution is simple, and easy to understand, so don`t hesitate to use it as a solution of your homework.

If it's not what You are looking for type in the equation solver your own equation and let us solve it.

Solution for 2x^2+4x-81=0 equation:


Simplifying
2x2 + 4x + -81 = 0

Reorder the terms:
-81 + 4x + 2x2 = 0

Solving
-81 + 4x + 2x2 = 0

Solving for variable 'x'.

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

Divide each side by '2'.
-40.5 + 2x + x2 = 0

Move the constant term to the right:

Add '40.5' to each side of the equation.
-40.5 + 2x + 40.5 + x2 = 0 + 40.5

Reorder the terms:
-40.5 + 40.5 + 2x + x2 = 0 + 40.5

Combine like terms: -40.5 + 40.5 = 0.0
0.0 + 2x + x2 = 0 + 40.5
2x + x2 = 0 + 40.5

Combine like terms: 0 + 40.5 = 40.5
2x + x2 = 40.5

The x term is 2x.  Take half its coefficient (1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
2x + 1 + x2 = 40.5 + 1

Reorder the terms:
1 + 2x + x2 = 40.5 + 1

Combine like terms: 40.5 + 1 = 41.5
1 + 2x + x2 = 41.5

Factor a perfect square on the left side:
(x + 1)(x + 1) = 41.5

Calculate the square root of the right side: 6.442049363

Break this problem into two subproblems by setting 
(x + 1) equal to 6.442049363 and -6.442049363.

Subproblem 1

x + 1 = 6.442049363 Simplifying x + 1 = 6.442049363 Reorder the terms: 1 + x = 6.442049363 Solving 1 + x = 6.442049363 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1' to each side of the equation. 1 + -1 + x = 6.442049363 + -1 Combine like terms: 1 + -1 = 0 0 + x = 6.442049363 + -1 x = 6.442049363 + -1 Combine like terms: 6.442049363 + -1 = 5.442049363 x = 5.442049363 Simplifying x = 5.442049363

Subproblem 2

x + 1 = -6.442049363 Simplifying x + 1 = -6.442049363 Reorder the terms: 1 + x = -6.442049363 Solving 1 + x = -6.442049363 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1' to each side of the equation. 1 + -1 + x = -6.442049363 + -1 Combine like terms: 1 + -1 = 0 0 + x = -6.442049363 + -1 x = -6.442049363 + -1 Combine like terms: -6.442049363 + -1 = -7.442049363 x = -7.442049363 Simplifying x = -7.442049363

Solution

The solution to the problem is based on the solutions from the subproblems. x = {5.442049363, -7.442049363}

See similar equations:

| 5(8+7x)=180 | | -x^2+11x=12 | | h=-16t^2+35t+4 | | 9x+27=8 | | 14y^2+28y=0 | | 3(9-8x-8x-4x)+8(3x+4)=11 | | 0=-16t^2+-6t+144 | | m^2-5m=-4 | | -7(-3v+2y-6)= | | 30=4+2c | | x^2+x=84 | | x^2-9/5x-20 | | sin(3.14/3)x | | 28+6x= | | 5/10-3/10= | | 3d+4d+5d=6d+7d+8 | | -8p-2(1-9p)=7(p-8) | | 84-x=168 | | 7x-4y=-76.4 | | (2x+2)*x=84 | | (x+2)/3-(2-x)/6=x-2 | | 4x+5=y | | X-1/9=o | | 0=-16t^2+20t+0 | | 3a-2=12-8 | | 1.5x=x+200 | | 55y=825 | | (2x+2)*(X)=84 | | x=(10000-x)/0.06 | | -40x+50y=200 | | 11x+15=5x+9 | | 55y= |

Equations solver categories