2x^2+4x+21=0

Simple and best practice solution for 2x^2+4x+21=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+21=0 equation:


Simplifying
2x2 + 4x + 21 = 0

Reorder the terms:
21 + 4x + 2x2 = 0

Solving
21 + 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'.
10.5 + 2x + x2 = 0

Move the constant term to the right:

Add '-10.5' to each side of the equation.
10.5 + 2x + -10.5 + x2 = 0 + -10.5

Reorder the terms:
10.5 + -10.5 + 2x + x2 = 0 + -10.5

Combine like terms: 10.5 + -10.5 = 0.0
0.0 + 2x + x2 = 0 + -10.5
2x + x2 = 0 + -10.5

Combine like terms: 0 + -10.5 = -10.5
2x + x2 = -10.5

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 = -10.5 + 1

Reorder the terms:
1 + 2x + x2 = -10.5 + 1

Combine like terms: -10.5 + 1 = -9.5
1 + 2x + x2 = -9.5

Factor a perfect square on the left side:
(x + 1)(x + 1) = -9.5

Can't calculate square root of the right side.

The solution to this equation could not be determined.

See similar equations:

| x^2+25x-259=0 | | 10x+8=8x+2 | | 9x+9=9x+1 | | 20x+9=7x+1 | | 2/3j=-12 | | 3/4j=-12 | | 3x+2=1x+7 | | 14x+1=4x+2 | | r=x*(0.6-x)*(1.2-x) | | 10x+3=4x+9 | | 5x-2=1x+7 | | 3x^3=8+x | | 3x^2+3x+23=0 | | (9-8x)(8x+9)-72=x(4-60) | | 2x=20-14 | | 5w-3y+7=0 | | 2x+6-6=24-6 | | (2x-3)/(2=x-6)/3 | | 5x+4-4=29-4 | | 3x+4-4=28-4 | | x+(x*0.1)=218 | | (-2xy)-4xy-(-xy)= | | 1/2/-2/5 | | Ln(x)=0.04305949 | | -10=-14+x | | 9x+4.79=2x+12 | | (-11y)-(-5y)-2y= | | 0.5x+10.1=x-6.95 | | -11-5y-2y= | | 0.4x+11.3=x-8.2 | | -11-4xy-xy= | | -7x+3y=19 |

Equations solver categories