21x^2+14x-40=0

Simple and best practice solution for 21x^2+14x-40=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 21x^2+14x-40=0 equation:


Simplifying
21x2 + 14x + -40 = 0

Reorder the terms:
-40 + 14x + 21x2 = 0

Solving
-40 + 14x + 21x2 = 0

Solving for variable 'x'.

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

Divide each side by '21'.
-1.904761905 + 0.6666666667x + x2 = 0

Move the constant term to the right:

Add '1.904761905' to each side of the equation.
-1.904761905 + 0.6666666667x + 1.904761905 + x2 = 0 + 1.904761905

Reorder the terms:
-1.904761905 + 1.904761905 + 0.6666666667x + x2 = 0 + 1.904761905

Combine like terms: -1.904761905 + 1.904761905 = 0.000000000
0.000000000 + 0.6666666667x + x2 = 0 + 1.904761905
0.6666666667x + x2 = 0 + 1.904761905

Combine like terms: 0 + 1.904761905 = 1.904761905
0.6666666667x + x2 = 1.904761905

The x term is 0.6666666667x.  Take half its coefficient (0.3333333334).
Square it (0.1111111112) and add it to both sides.

Add '0.1111111112' to each side of the equation.
0.6666666667x + 0.1111111112 + x2 = 1.904761905 + 0.1111111112

Reorder the terms:
0.1111111112 + 0.6666666667x + x2 = 1.904761905 + 0.1111111112

Combine like terms: 1.904761905 + 0.1111111112 = 2.0158730162
0.1111111112 + 0.6666666667x + x2 = 2.0158730162

Factor a perfect square on the left side:
(x + 0.3333333334)(x + 0.3333333334) = 2.0158730162

Calculate the square root of the right side: 1.41981443

Break this problem into two subproblems by setting 
(x + 0.3333333334) equal to 1.41981443 and -1.41981443.

Subproblem 1

x + 0.3333333334 = 1.41981443 Simplifying x + 0.3333333334 = 1.41981443 Reorder the terms: 0.3333333334 + x = 1.41981443 Solving 0.3333333334 + x = 1.41981443 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.3333333334' to each side of the equation. 0.3333333334 + -0.3333333334 + x = 1.41981443 + -0.3333333334 Combine like terms: 0.3333333334 + -0.3333333334 = 0.0000000000 0.0000000000 + x = 1.41981443 + -0.3333333334 x = 1.41981443 + -0.3333333334 Combine like terms: 1.41981443 + -0.3333333334 = 1.0864810966 x = 1.0864810966 Simplifying x = 1.0864810966

Subproblem 2

x + 0.3333333334 = -1.41981443 Simplifying x + 0.3333333334 = -1.41981443 Reorder the terms: 0.3333333334 + x = -1.41981443 Solving 0.3333333334 + x = -1.41981443 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.3333333334' to each side of the equation. 0.3333333334 + -0.3333333334 + x = -1.41981443 + -0.3333333334 Combine like terms: 0.3333333334 + -0.3333333334 = 0.0000000000 0.0000000000 + x = -1.41981443 + -0.3333333334 x = -1.41981443 + -0.3333333334 Combine like terms: -1.41981443 + -0.3333333334 = -1.7531477634 x = -1.7531477634 Simplifying x = -1.7531477634

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.0864810966, -1.7531477634}

See similar equations:

| 7+x(7)=3 | | 2x-5yi=4+15i | | 4/16-15/25 | | 15-3t=17-t | | 56+x=5(8+x) | | 7y^2-8=73 | | p-3q=2 | | 3x+8x=3x-5 | | 3p-7=3p+11 | | 4x+4+4x+4x+3=180 | | 4=k+8 | | -3x^2-24x+36=10 | | 3x+y=51 | | 3x^2+3y^2+3z^2-x+6y+3z=9 | | (u-3)(u+4)= | | -3x^2-24x+12=10 | | (2y-7)=(14-2)+4y | | ((5^(-1/2))*(5x^(5/2)))/(5x)^(3/2) | | y=-5/7x | | 1/10x^3-15/2-25 | | 8-2(4-1)= | | x^2-2xy+y^2-6x-6y-1=0 | | 8x+4(-2x-1)=-4 | | x^2+2xy+y^2-6x-6y-1=0 | | 1/2x-5/6=2x-3/4 | | 64.5x/6-3x/4=x-11 | | q-p=6 | | 2x-4=5+6x | | (Y)=7 | | 9p+3q=-2 | | 3z+6(z+3)-10= | | 4y+4y=-16 |

Equations solver categories