3x^2-81x-7=0

Simple and best practice solution for 3x^2-81x-7=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 3x^2-81x-7=0 equation:


Simplifying
3x2 + -81x + -7 = 0

Reorder the terms:
-7 + -81x + 3x2 = 0

Solving
-7 + -81x + 3x2 = 0

Solving for variable 'x'.

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

Divide each side by '3'.
-2.333333333 + -27x + x2 = 0

Move the constant term to the right:

Add '2.333333333' to each side of the equation.
-2.333333333 + -27x + 2.333333333 + x2 = 0 + 2.333333333

Reorder the terms:
-2.333333333 + 2.333333333 + -27x + x2 = 0 + 2.333333333

Combine like terms: -2.333333333 + 2.333333333 = 0.000000000
0.000000000 + -27x + x2 = 0 + 2.333333333
-27x + x2 = 0 + 2.333333333

Combine like terms: 0 + 2.333333333 = 2.333333333
-27x + x2 = 2.333333333

The x term is -27x.  Take half its coefficient (-13.5).
Square it (182.25) and add it to both sides.

Add '182.25' to each side of the equation.
-27x + 182.25 + x2 = 2.333333333 + 182.25

Reorder the terms:
182.25 + -27x + x2 = 2.333333333 + 182.25

Combine like terms: 2.333333333 + 182.25 = 184.583333333
182.25 + -27x + x2 = 184.583333333

Factor a perfect square on the left side:
(x + -13.5)(x + -13.5) = 184.583333333

Calculate the square root of the right side: 13.586144903

Break this problem into two subproblems by setting 
(x + -13.5) equal to 13.586144903 and -13.586144903.

Subproblem 1

x + -13.5 = 13.586144903 Simplifying x + -13.5 = 13.586144903 Reorder the terms: -13.5 + x = 13.586144903 Solving -13.5 + x = 13.586144903 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '13.5' to each side of the equation. -13.5 + 13.5 + x = 13.586144903 + 13.5 Combine like terms: -13.5 + 13.5 = 0.0 0.0 + x = 13.586144903 + 13.5 x = 13.586144903 + 13.5 Combine like terms: 13.586144903 + 13.5 = 27.086144903 x = 27.086144903 Simplifying x = 27.086144903

Subproblem 2

x + -13.5 = -13.586144903 Simplifying x + -13.5 = -13.586144903 Reorder the terms: -13.5 + x = -13.586144903 Solving -13.5 + x = -13.586144903 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '13.5' to each side of the equation. -13.5 + 13.5 + x = -13.586144903 + 13.5 Combine like terms: -13.5 + 13.5 = 0.0 0.0 + x = -13.586144903 + 13.5 x = -13.586144903 + 13.5 Combine like terms: -13.586144903 + 13.5 = -0.086144903 x = -0.086144903 Simplifying x = -0.086144903

Solution

The solution to the problem is based on the solutions from the subproblems. x = {27.086144903, -0.086144903}

See similar equations:

| 16=-40x-(-8x-4) | | 4x+8=-(-14x+12) | | 1/7m-6=3/7m-4 | | 11t+15=95-16t | | -25/4=-10x-3(-2x+3/4) | | g(x)=logx | | 11-x=-(2x-3) | | -0.6=1.4x | | 5x+45+3x-25=480 | | 0.20x+0.35(50)=34.5 | | m(m+4)(m-6)=0 | | -3.6-1.4x=-5x+5x-3 | | H(t)=-16t+96t+880 | | 2x-5(-5x-13)=-70 | | 3x+1=3(x-6) | | 175x-1x^2=3100 | | 7+7(1-2x)=84 | | D+9-2d=6 | | -1.4x=3.6-3 | | 10x-5x=45 | | 4x-8=13-x | | -3.6-1.4x=-5x-(-5x+3) | | 4x-8=13-7 | | 5cm*25cm*2cm= | | x+(x+2)+(x+4)+(x+6)+(x+8)+(x+10)+(x+12)= | | 12y+6x=30 | | 89=4x+8+7x-2y | | y^2+2y+1=2y^2+5y+3 | | 1/10n=1/2 | | V-36=-16 | | 20x^4+72x^2+16=0 | | 4x-6=-2x+8-3x |

Equations solver categories