0=x^2-3x-9

Simple and best practice solution for 0=x^2-3x-9 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 0=x^2-3x-9 equation:


Simplifying
0 = x2 + -3x + -9

Reorder the terms:
0 = -9 + -3x + x2

Solving
0 = -9 + -3x + x2

Solving for variable 'x'.

Combine like terms: 0 + 9 = 9
9 + 3x + -1x2 = -9 + -3x + x2 + 9 + 3x + -1x2

Reorder the terms:
9 + 3x + -1x2 = -9 + 9 + -3x + 3x + x2 + -1x2

Combine like terms: -9 + 9 = 0
9 + 3x + -1x2 = 0 + -3x + 3x + x2 + -1x2
9 + 3x + -1x2 = -3x + 3x + x2 + -1x2

Combine like terms: -3x + 3x = 0
9 + 3x + -1x2 = 0 + x2 + -1x2
9 + 3x + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
9 + 3x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-9 + -3x + x2 = 0

Move the constant term to the right:

Add '9' to each side of the equation.
-9 + -3x + 9 + x2 = 0 + 9

Reorder the terms:
-9 + 9 + -3x + x2 = 0 + 9

Combine like terms: -9 + 9 = 0
0 + -3x + x2 = 0 + 9
-3x + x2 = 0 + 9

Combine like terms: 0 + 9 = 9
-3x + x2 = 9

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 = 9 + 2.25

Reorder the terms:
2.25 + -3x + x2 = 9 + 2.25

Combine like terms: 9 + 2.25 = 11.25
2.25 + -3x + x2 = 11.25

Factor a perfect square on the left side:
(x + -1.5)(x + -1.5) = 11.25

Calculate the square root of the right side: 3.354101966

Break this problem into two subproblems by setting 
(x + -1.5) equal to 3.354101966 and -3.354101966.

Subproblem 1

x + -1.5 = 3.354101966 Simplifying x + -1.5 = 3.354101966 Reorder the terms: -1.5 + x = 3.354101966 Solving -1.5 + x = 3.354101966 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 = 3.354101966 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = 3.354101966 + 1.5 x = 3.354101966 + 1.5 Combine like terms: 3.354101966 + 1.5 = 4.854101966 x = 4.854101966 Simplifying x = 4.854101966

Subproblem 2

x + -1.5 = -3.354101966 Simplifying x + -1.5 = -3.354101966 Reorder the terms: -1.5 + x = -3.354101966 Solving -1.5 + x = -3.354101966 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 = -3.354101966 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = -3.354101966 + 1.5 x = -3.354101966 + 1.5 Combine like terms: -3.354101966 + 1.5 = -1.854101966 x = -1.854101966 Simplifying x = -1.854101966

Solution

The solution to the problem is based on the solutions from the subproblems. x = {4.854101966, -1.854101966}

See similar equations:

| 9c-35=46 | | 0=-6(x-7) | | x+1=-2x+11 | | -z+9y=6 | | 2(x+4)+2=9x+2(x+2) | | 12x+4=10x-16 | | 9y-z=6 | | 36=.06x+x | | 7x-4=6x+9 | | 5t-16=59 | | 3/5-n=1/10 | | 1,250/3 | | 4g-25=3 | | 0=-1A+5B | | 8y-23=-9+6y | | 23(2.2)= | | 3-x^2=10x | | 15w-65=10 | | -.75n=-100 | | 5(x+5)+3=10x+5(x+3) | | w-16=14 | | 5(5-4)+2x=14 | | 0.7-4=0.9 | | 45=-5(7-8x) | | 3x^2-2y-3=0 | | 21-12n=12 | | 4036/3= | | 3x+2=20-3x | | 3/4t-1/2=3/4 | | 4b+3p=12 | | -13=x/10-12 | | 4J=400 |

Equations solver categories