x^2-8x-15=0

Simple and best practice solution for x^2-8x-15=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^2-8x-15=0 equation:


Simplifying
x2 + -8x + -15 = 0

Reorder the terms:
-15 + -8x + x2 = 0

Solving
-15 + -8x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '15' to each side of the equation.
-15 + -8x + 15 + x2 = 0 + 15

Reorder the terms:
-15 + 15 + -8x + x2 = 0 + 15

Combine like terms: -15 + 15 = 0
0 + -8x + x2 = 0 + 15
-8x + x2 = 0 + 15

Combine like terms: 0 + 15 = 15
-8x + x2 = 15

The x term is -8x.  Take half its coefficient (-4).
Square it (16) and add it to both sides.

Add '16' to each side of the equation.
-8x + 16 + x2 = 15 + 16

Reorder the terms:
16 + -8x + x2 = 15 + 16

Combine like terms: 15 + 16 = 31
16 + -8x + x2 = 31

Factor a perfect square on the left side:
(x + -4)(x + -4) = 31

Calculate the square root of the right side: 5.567764363

Break this problem into two subproblems by setting 
(x + -4) equal to 5.567764363 and -5.567764363.

Subproblem 1

x + -4 = 5.567764363 Simplifying x + -4 = 5.567764363 Reorder the terms: -4 + x = 5.567764363 Solving -4 + x = 5.567764363 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4' to each side of the equation. -4 + 4 + x = 5.567764363 + 4 Combine like terms: -4 + 4 = 0 0 + x = 5.567764363 + 4 x = 5.567764363 + 4 Combine like terms: 5.567764363 + 4 = 9.567764363 x = 9.567764363 Simplifying x = 9.567764363

Subproblem 2

x + -4 = -5.567764363 Simplifying x + -4 = -5.567764363 Reorder the terms: -4 + x = -5.567764363 Solving -4 + x = -5.567764363 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4' to each side of the equation. -4 + 4 + x = -5.567764363 + 4 Combine like terms: -4 + 4 = 0 0 + x = -5.567764363 + 4 x = -5.567764363 + 4 Combine like terms: -5.567764363 + 4 = -1.567764363 x = -1.567764363 Simplifying x = -1.567764363

Solution

The solution to the problem is based on the solutions from the subproblems. x = {9.567764363, -1.567764363}

See similar equations:

| x+17=-19 | | 1536=6x^2 | | 225-7x=29x+21 | | 5a-20=-5+8a | | 2z^2+7z-15=0 | | (9-0.8x)(5-0.5x)=0 | | 9s^2+3s-20= | | 183-4x=23x+24 | | 14-8x=90-22x | | 7.6=y-5 | | 186-6x=6x+6 | | 7x-19.4=4x+10 | | -15-2=6x+6 | | X^2+x-182=0 | | (x)(x-5)=24 | | 2(1-3x)-2(4x-5)=-2 | | 112-4x=3x+14 | | 3x-(6x+2)=-3x+2 | | y^2+y-42= | | 4x-1=50+x | | 4x+13=-107-8x | | 2.7+0.3x=0.6 | | y^2+y-45= | | 2x-5=99 | | -12a=-3-13 | | 3.6x-25=1.4x+8 | | 2x-6=9x-41 | | -5(m+2)-m-7=-6(m+5)+13 | | 0.4x+0.1=-0.3 | | x-1=5.76 | | 5x+39=14x-69 | | (5x+4)*(2x^2-9x+9)=0 |

Equations solver categories