x^2+3x-81=0

Simple and best practice solution for x^2+3x-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+3x-81=0 equation:


Simplifying
x2 + 3x + -81 = 0

Reorder the terms:
-81 + 3x + x2 = 0

Solving
-81 + 3x + 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 + 3x + 81 + x2 = 0 + 81

Reorder the terms:
-81 + 81 + 3x + x2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + 3x + x2 = 0 + 81
3x + x2 = 0 + 81

Combine like terms: 0 + 81 = 81
3x + x2 = 81

The x term is 3x.  Take half its coefficient (1.5).
Square it (2.25) and add it to both sides.

Add '2.25' to each side of the equation.
3x + 2.25 + x2 = 81 + 2.25

Reorder the terms:
2.25 + 3x + x2 = 81 + 2.25

Combine like terms: 81 + 2.25 = 83.25
2.25 + 3x + x2 = 83.25

Factor a perfect square on the left side:
(x + 1.5)(x + 1.5) = 83.25

Calculate the square root of the right side: 9.124143795

Break this problem into two subproblems by setting 
(x + 1.5) equal to 9.124143795 and -9.124143795.

Subproblem 1

x + 1.5 = 9.124143795 Simplifying x + 1.5 = 9.124143795 Reorder the terms: 1.5 + x = 9.124143795 Solving 1.5 + x = 9.124143795 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.5' to each side of the equation. 1.5 + -1.5 + x = 9.124143795 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = 9.124143795 + -1.5 x = 9.124143795 + -1.5 Combine like terms: 9.124143795 + -1.5 = 7.624143795 x = 7.624143795 Simplifying x = 7.624143795

Subproblem 2

x + 1.5 = -9.124143795 Simplifying x + 1.5 = -9.124143795 Reorder the terms: 1.5 + x = -9.124143795 Solving 1.5 + x = -9.124143795 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.5' to each side of the equation. 1.5 + -1.5 + x = -9.124143795 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = -9.124143795 + -1.5 x = -9.124143795 + -1.5 Combine like terms: -9.124143795 + -1.5 = -10.624143795 x = -10.624143795 Simplifying x = -10.624143795

Solution

The solution to the problem is based on the solutions from the subproblems. x = {7.624143795, -10.624143795}

See similar equations:

| 2x^2+17x-448=0 | | 9x^2-28x+40=0 | | 3x^3-14x^2+40x=0 | | 5x+3=-7x-117 | | 98=7x+4x-1 | | (33+19+x)/3=25 | | 4-3x-2x=-46 | | 4-3x-2x=46 | | 6(x+20)=5(5x-14) | | X+0.08X=23219.25 | | 3(x-2)-2(3x+4)+62=0 | | 240-4x+x=12x-3x | | 9x+10x-6x=234 | | -x^2+10x=-14 | | 33-x/5x=2 | | 4x^2-4x+64=0 | | 9x^2+2kx-1=0 | | 2x+9=4x-19 | | 5[12-(6-3x)-2x]=2(1-x) | | x-3=2-4x | | X^5=16 | | 18x^6y-3x^5y^2= | | 5(t+1)+8=3(t-2)+6 | | W(2w+3)=560 | | 2w(w+3)=560 | | 27x-36=15x+108 | | 17x=40 | | 3m^2-12m^2+75m= | | -16(x+6)=49(x-14) | | 1=1-6t+4t | | 9(x+1)=-39(x+33) | | -75=-15b |

Equations solver categories