x*x-4x=9

Simple and best practice solution for x*x-4x=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 x*x-4x=9 equation:


Simplifying
x * x + -4x = 9

Multiply x * x
x2 + -4x = 9

Reorder the terms:
-4x + x2 = 9

Solving
-4x + x2 = 9

Solving for variable 'x'.

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

Combine like terms: 9 + -9 = 0
-9 + -4x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '9' to each side of the equation.
-9 + -4x + 9 + x2 = 0 + 9

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

Combine like terms: -9 + 9 = 0
0 + -4x + x2 = 0 + 9
-4x + x2 = 0 + 9

Combine like terms: 0 + 9 = 9
-4x + x2 = 9

The x term is -4x.  Take half its coefficient (-2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
-4x + 4 + x2 = 9 + 4

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

Combine like terms: 9 + 4 = 13
4 + -4x + x2 = 13

Factor a perfect square on the left side:
(x + -2)(x + -2) = 13

Calculate the square root of the right side: 3.605551275

Break this problem into two subproblems by setting 
(x + -2) equal to 3.605551275 and -3.605551275.

Subproblem 1

x + -2 = 3.605551275 Simplifying x + -2 = 3.605551275 Reorder the terms: -2 + x = 3.605551275 Solving -2 + x = 3.605551275 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2' to each side of the equation. -2 + 2 + x = 3.605551275 + 2 Combine like terms: -2 + 2 = 0 0 + x = 3.605551275 + 2 x = 3.605551275 + 2 Combine like terms: 3.605551275 + 2 = 5.605551275 x = 5.605551275 Simplifying x = 5.605551275

Subproblem 2

x + -2 = -3.605551275 Simplifying x + -2 = -3.605551275 Reorder the terms: -2 + x = -3.605551275 Solving -2 + x = -3.605551275 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2' to each side of the equation. -2 + 2 + x = -3.605551275 + 2 Combine like terms: -2 + 2 = 0 0 + x = -3.605551275 + 2 x = -3.605551275 + 2 Combine like terms: -3.605551275 + 2 = -1.605551275 x = -1.605551275 Simplifying x = -1.605551275

Solution

The solution to the problem is based on the solutions from the subproblems. x = {5.605551275, -1.605551275}

See similar equations:

| x^2+8x+3sqrt(x^2+8x)=18 | | 8-(5x-7)+6x=8 | | x^2+8x+3xsqrt(x^2+8x)=18 | | 9/(2x-1)=15/3x | | 3(4-5x)=4x-(4+3x-x)+3x+1 | | -3(x+3)-x-4=-4(x+5)+7 | | -m=24 | | -3/14=x/14 | | L+4=13 | | 3z+25=2z | | x/3=5.1 | | 4=14-m | | 2=-16+n | | 25+.20n=30+.10n | | -7/12x=3 | | 2-5j=62 | | 50x+20y=15 | | 2x^2-26x= | | x+.09=18966 | | 99=9p | | 6(3s+7)=114 | | 4+2(5x+1)=-14 | | X(2x+5)=(2x+3)(x+4) | | 5(2l+1)=95 | | 7x-8+12x=30 | | -6x+-1x=4 | | (x+1)11=(x+4)1 | | 19/8×24/19 | | 8x+5y+8z-3x+4z-7y= | | 6m+-15=-37 | | -2(1-7x)-5x=34 | | 9y-3(y-4)=18 |

Equations solver categories