2x^2-4x-15=0

Simple and best practice solution for 2x^2-4x-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 2x^2-4x-15=0 equation:


Simplifying
2x2 + -4x + -15 = 0

Reorder the terms:
-15 + -4x + 2x2 = 0

Solving
-15 + -4x + 2x2 = 0

Solving for variable 'x'.

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

Divide each side by '2'.
-7.5 + -2x + x2 = 0

Move the constant term to the right:

Add '7.5' to each side of the equation.
-7.5 + -2x + 7.5 + x2 = 0 + 7.5

Reorder the terms:
-7.5 + 7.5 + -2x + x2 = 0 + 7.5

Combine like terms: -7.5 + 7.5 = 0.0
0.0 + -2x + x2 = 0 + 7.5
-2x + x2 = 0 + 7.5

Combine like terms: 0 + 7.5 = 7.5
-2x + x2 = 7.5

The x term is -2x.  Take half its coefficient (-1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
-2x + 1 + x2 = 7.5 + 1

Reorder the terms:
1 + -2x + x2 = 7.5 + 1

Combine like terms: 7.5 + 1 = 8.5
1 + -2x + x2 = 8.5

Factor a perfect square on the left side:
(x + -1)(x + -1) = 8.5

Calculate the square root of the right side: 2.915475947

Break this problem into two subproblems by setting 
(x + -1) equal to 2.915475947 and -2.915475947.

Subproblem 1

x + -1 = 2.915475947 Simplifying x + -1 = 2.915475947 Reorder the terms: -1 + x = 2.915475947 Solving -1 + x = 2.915475947 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1' to each side of the equation. -1 + 1 + x = 2.915475947 + 1 Combine like terms: -1 + 1 = 0 0 + x = 2.915475947 + 1 x = 2.915475947 + 1 Combine like terms: 2.915475947 + 1 = 3.915475947 x = 3.915475947 Simplifying x = 3.915475947

Subproblem 2

x + -1 = -2.915475947 Simplifying x + -1 = -2.915475947 Reorder the terms: -1 + x = -2.915475947 Solving -1 + x = -2.915475947 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1' to each side of the equation. -1 + 1 + x = -2.915475947 + 1 Combine like terms: -1 + 1 = 0 0 + x = -2.915475947 + 1 x = -2.915475947 + 1 Combine like terms: -2.915475947 + 1 = -1.915475947 x = -1.915475947 Simplifying x = -1.915475947

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.915475947, -1.915475947}

See similar equations:

| g/3.72=8.37 | | F(x)=8x^2+53x-21 | | 4z^2/y^2+16y+64=25x^2 | | 5x--10=-7x+1 | | 12y^2=1-4y | | 6t-15=11+4t | | -6.3z=34.65 | | 5x--10=19 | | 4p^2+4=12p | | 81-c^2=0 | | -2(8+6x)=-88 | | 2x-11=85 | | 8-X^2=X | | 4x^2+16x+104=5 | | P(x)=x^3-512 | | y-.9=.8y-.4 | | x/4+1/3=x-26/3 | | 2.5B-52=4h | | x/4+1/3=x-8/2/3 | | 36b^8j^6/49 | | y=1/3-4 | | 8r(3r-1)(r+2)=0 | | -3+15=12x-2-11x | | (X^2+5x-5)/x+3 | | 3x+2=2(x+4) | | -(6xy-10)+2(5xy+7)= | | -4(x+2)=0 | | 4(t-2)+8t=6(2t+3)-13 | | -5x-18=32 | | (3x-4)(x-8)= | | 15x-35x^2=0 | | -2(4s-2)-4=-3(4s+5)-4 |

Equations solver categories