2x^2+2x-21=0

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


Simplifying
2x2 + 2x + -21 = 0

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

Solving
-21 + 2x + 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 + x + x2 = 0

Move the constant term to the right:

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

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

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

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

The x term is x.  Take half its coefficient (0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
 + 0.25 + x2 = 10.5 + 0.25

Combine like terms:  + 0.25 = 1.25
1.25 + x2 = 10.5 + 0.25

Combine like terms: 10.5 + 0.25 = 10.75
1.25 + x2 = 10.75

Factor a perfect square on the left side:
(x + 0.5)(x + 0.5) = 10.75

Calculate the square root of the right side: 3.278719262

Break this problem into two subproblems by setting 
(x + 0.5) equal to 3.278719262 and -3.278719262.

Subproblem 1

x + 0.5 = 3.278719262 Simplifying x + 0.5 = 3.278719262 Reorder the terms: 0.5 + x = 3.278719262 Solving 0.5 + x = 3.278719262 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5' to each side of the equation. 0.5 + -0.5 + x = 3.278719262 + -0.5 Combine like terms: 0.5 + -0.5 = 0.0 0.0 + x = 3.278719262 + -0.5 x = 3.278719262 + -0.5 Combine like terms: 3.278719262 + -0.5 = 2.778719262 x = 2.778719262 Simplifying x = 2.778719262

Subproblem 2

x + 0.5 = -3.278719262 Simplifying x + 0.5 = -3.278719262 Reorder the terms: 0.5 + x = -3.278719262 Solving 0.5 + x = -3.278719262 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5' to each side of the equation. 0.5 + -0.5 + x = -3.278719262 + -0.5 Combine like terms: 0.5 + -0.5 = 0.0 0.0 + x = -3.278719262 + -0.5 x = -3.278719262 + -0.5 Combine like terms: -3.278719262 + -0.5 = -3.778719262 x = -3.778719262 Simplifying x = -3.778719262

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.778719262, -3.778719262}

See similar equations:

| .12(y-5)+.10y=.02y-.09(20) | | 10a+2-3a= | | 5x+11-8=33 | | a=8.5*11 | | x(x+2)=60 | | 9x+5x=15-3 | | 2(120-22n)=105-4n | | -3y-3=5-2y | | -4x+3=10 | | 3-2(x-1)=3(x-5) | | 7(a+2b)= | | 125m-100+43200=46125-200m | | 3(m-4)+1=2(m+3) | | -5p-16=54 | | Ix-5l=10 | | A(9+9a)=40 | | 6n+3n+8=0 | | .50x+.20(160)=.25(40) | | 15-2(4x-1)=-10x+7 | | 8n-(2n-3)+3=12 | | p+prt=a | | -7+2x=17 | | 63-3p= | | 24+(1.50*n)=3*n | | x^2+14x=0.005 | | 5-[2X-(X+5)]=2-(X+3) | | 14x(3x-7)=29 | | 7y-9=19 | | -3x(x+2)=16-x | | 4.2p=12.6 | | 24.55+a-15.60=125.45 | | Y=.8x+12 |

Equations solver categories