9x^2+4x-81=0

Simple and best practice solution for 9x^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 9x^2+4x-81=0 equation:


Simplifying
9x2 + 4x + -81 = 0

Reorder the terms:
-81 + 4x + 9x2 = 0

Solving
-81 + 4x + 9x2 = 0

Solving for variable 'x'.

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

Divide each side by '9'.
-9 + 0.4444444444x + x2 = 0

Move the constant term to the right:

Add '9' to each side of the equation.
-9 + 0.4444444444x + 9 + x2 = 0 + 9

Reorder the terms:
-9 + 9 + 0.4444444444x + x2 = 0 + 9

Combine like terms: -9 + 9 = 0
0 + 0.4444444444x + x2 = 0 + 9
0.4444444444x + x2 = 0 + 9

Combine like terms: 0 + 9 = 9
0.4444444444x + x2 = 9

The x term is 0.4444444444x.  Take half its coefficient (0.2222222222).
Square it (0.04938271604) and add it to both sides.

Add '0.04938271604' to each side of the equation.
0.4444444444x + 0.04938271604 + x2 = 9 + 0.04938271604

Reorder the terms:
0.04938271604 + 0.4444444444x + x2 = 9 + 0.04938271604

Combine like terms: 9 + 0.04938271604 = 9.04938271604
0.04938271604 + 0.4444444444x + x2 = 9.04938271604

Factor a perfect square on the left side:
(x + 0.2222222222)(x + 0.2222222222) = 9.04938271604

Calculate the square root of the right side: 3.008219193

Break this problem into two subproblems by setting 
(x + 0.2222222222) equal to 3.008219193 and -3.008219193.

Subproblem 1

x + 0.2222222222 = 3.008219193 Simplifying x + 0.2222222222 = 3.008219193 Reorder the terms: 0.2222222222 + x = 3.008219193 Solving 0.2222222222 + x = 3.008219193 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2222222222' to each side of the equation. 0.2222222222 + -0.2222222222 + x = 3.008219193 + -0.2222222222 Combine like terms: 0.2222222222 + -0.2222222222 = 0.0000000000 0.0000000000 + x = 3.008219193 + -0.2222222222 x = 3.008219193 + -0.2222222222 Combine like terms: 3.008219193 + -0.2222222222 = 2.7859969708 x = 2.7859969708 Simplifying x = 2.7859969708

Subproblem 2

x + 0.2222222222 = -3.008219193 Simplifying x + 0.2222222222 = -3.008219193 Reorder the terms: 0.2222222222 + x = -3.008219193 Solving 0.2222222222 + x = -3.008219193 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2222222222' to each side of the equation. 0.2222222222 + -0.2222222222 + x = -3.008219193 + -0.2222222222 Combine like terms: 0.2222222222 + -0.2222222222 = 0.0000000000 0.0000000000 + x = -3.008219193 + -0.2222222222 x = -3.008219193 + -0.2222222222 Combine like terms: -3.008219193 + -0.2222222222 = -3.2304414152 x = -3.2304414152 Simplifying x = -3.2304414152

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.7859969708, -3.2304414152}

See similar equations:

| 3xsquared+11x=4 | | -4+.666y=.5y-5 | | 8/93/21 | | x=3x-127 | | 20=q | | 0.14y-1.6+3.12y+3.6= | | -6-3(2k-4)=18 | | a/3=-0.2 | | (9x+5)-(12x+7)= | | 3.4(2x+5)=-.2(2x+5) | | 12.3x=27.06 | | .5x+5=.33333333333333333333333333333333x+7 | | 4x^2(x-1)=0 | | 418=22x | | 1/4÷2/7= | | 28-4x/3=x | | 6-x=d | | 2x-44=-3 | | 12=8-f | | 4x+5y-6x-y= | | .07x+x=5 | | X+2.6=58.4 | | 12.25xy= | | X+0.75=12.25 | | f(n)=5n+4n | | .2(b+10)-7=.3333333333333333333333333333333(b-9) | | 12.2=m+18.2 | | 10p^2-100p+20000=0 | | -6y-3=3y+15 | | .2(b+10)-7=.333333333333333333333(b-9) | | -7(f+1)=5(f-2) | | -6x-13=x-23 |

Equations solver categories