x^2+18x-81=0

Simple and best practice solution for x^2+18x-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 x^2+18x-81=0 equation:


Simplifying
x2 + 18x + -81 = 0

Reorder the terms:
-81 + 18x + x2 = 0

Solving
-81 + 18x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '81' to each side of the equation.
-81 + 18x + 81 + x2 = 0 + 81

Reorder the terms:
-81 + 81 + 18x + x2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + 18x + x2 = 0 + 81
18x + x2 = 0 + 81

Combine like terms: 0 + 81 = 81
18x + x2 = 81

The x term is 18x.  Take half its coefficient (9).
Square it (81) and add it to both sides.

Add '81' to each side of the equation.
18x + 81 + x2 = 81 + 81

Reorder the terms:
81 + 18x + x2 = 81 + 81

Combine like terms: 81 + 81 = 162
81 + 18x + x2 = 162

Factor a perfect square on the left side:
(x + 9)(x + 9) = 162

Calculate the square root of the right side: 12.727922061

Break this problem into two subproblems by setting 
(x + 9) equal to 12.727922061 and -12.727922061.

Subproblem 1

x + 9 = 12.727922061 Simplifying x + 9 = 12.727922061 Reorder the terms: 9 + x = 12.727922061 Solving 9 + x = 12.727922061 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + x = 12.727922061 + -9 Combine like terms: 9 + -9 = 0 0 + x = 12.727922061 + -9 x = 12.727922061 + -9 Combine like terms: 12.727922061 + -9 = 3.727922061 x = 3.727922061 Simplifying x = 3.727922061

Subproblem 2

x + 9 = -12.727922061 Simplifying x + 9 = -12.727922061 Reorder the terms: 9 + x = -12.727922061 Solving 9 + x = -12.727922061 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + x = -12.727922061 + -9 Combine like terms: 9 + -9 = 0 0 + x = -12.727922061 + -9 x = -12.727922061 + -9 Combine like terms: -12.727922061 + -9 = -21.727922061 x = -21.727922061 Simplifying x = -21.727922061

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.727922061, -21.727922061}

See similar equations:

| 49(y+1)=59y | | 2(x+3)+4(x+5)=50 | | 6p^3-9p^2+2p-3= | | 5+5x=6x-7 | | 2(x+3)+4(x+5)=56 | | 4x-2.5=9.5-2x | | 2.10+.80=11.60 | | 10x-177=3x-9 | | 11.70+.80m=2.10 | | 102-3x=15x+24 | | 6=29a | | x^2-1.5x-1.7=0 | | 12=9(5+x^2) | | 2(5f-11)=28 | | 4x+1+2x= | | 144-6x=2x+10 | | n=4(-5)-3 | | n=4(-6)-3 | | -3m+7=31 | | n=4(-7)-3 | | n=4(-8)-3 | | 1.6x-7=8 | | 7x^2-15x+54=0 | | (x+3)(x+4)=48 | | 3.5x-0.5x=0.2(3-x) | | .6x-7=8 | | 9y-6.9=6y | | 32=4y+8 | | 5x-17=-7+7 | | n=4(-1)-3 | | 8=28a | | n=4(-2)-3 |

Equations solver categories