21x^2-11x-21=0

Simple and best practice solution for 21x^2-11x-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 21x^2-11x-21=0 equation:


Simplifying
21x2 + -11x + -21 = 0

Reorder the terms:
-21 + -11x + 21x2 = 0

Solving
-21 + -11x + 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 + -0.5238095238x + x2 = 0

Move the constant term to the right:

Add '1' to each side of the equation.
-1 + -0.5238095238x + 1 + x2 = 0 + 1

Reorder the terms:
-1 + 1 + -0.5238095238x + x2 = 0 + 1

Combine like terms: -1 + 1 = 0
0 + -0.5238095238x + x2 = 0 + 1
-0.5238095238x + x2 = 0 + 1

Combine like terms: 0 + 1 = 1
-0.5238095238x + x2 = 1

The x term is -0.5238095238x.  Take half its coefficient (-0.2619047619).
Square it (0.06859410431) and add it to both sides.

Add '0.06859410431' to each side of the equation.
-0.5238095238x + 0.06859410431 + x2 = 1 + 0.06859410431

Reorder the terms:
0.06859410431 + -0.5238095238x + x2 = 1 + 0.06859410431

Combine like terms: 1 + 0.06859410431 = 1.06859410431
0.06859410431 + -0.5238095238x + x2 = 1.06859410431

Factor a perfect square on the left side:
(x + -0.2619047619)(x + -0.2619047619) = 1.06859410431

Calculate the square root of the right side: 1.033728255

Break this problem into two subproblems by setting 
(x + -0.2619047619) equal to 1.033728255 and -1.033728255.

Subproblem 1

x + -0.2619047619 = 1.033728255 Simplifying x + -0.2619047619 = 1.033728255 Reorder the terms: -0.2619047619 + x = 1.033728255 Solving -0.2619047619 + x = 1.033728255 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.2619047619' to each side of the equation. -0.2619047619 + 0.2619047619 + x = 1.033728255 + 0.2619047619 Combine like terms: -0.2619047619 + 0.2619047619 = 0.0000000000 0.0000000000 + x = 1.033728255 + 0.2619047619 x = 1.033728255 + 0.2619047619 Combine like terms: 1.033728255 + 0.2619047619 = 1.2956330169 x = 1.2956330169 Simplifying x = 1.2956330169

Subproblem 2

x + -0.2619047619 = -1.033728255 Simplifying x + -0.2619047619 = -1.033728255 Reorder the terms: -0.2619047619 + x = -1.033728255 Solving -0.2619047619 + x = -1.033728255 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.2619047619' to each side of the equation. -0.2619047619 + 0.2619047619 + x = -1.033728255 + 0.2619047619 Combine like terms: -0.2619047619 + 0.2619047619 = 0.0000000000 0.0000000000 + x = -1.033728255 + 0.2619047619 x = -1.033728255 + 0.2619047619 Combine like terms: -1.033728255 + 0.2619047619 = -0.7718234931 x = -0.7718234931 Simplifying x = -0.7718234931

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.2956330169, -0.7718234931}

See similar equations:

| -2=9z-2 | | 100(1.5)(1.5)(1.5)(1.5)(1.5)(1.5)(1.5)(1.5)=g | | 3x-22=44 | | x+10=2(x+3) | | u-9=27 | | 2(a-5)=40 | | 100(1.5)(1.5)(1.5)(1.5)(1.5)(1.5)(1.5)=g | | u=4(20) | | 100(1.5)(1.5)=a | | 16=4r-8 | | -789x+258-11x+456-894=336x+201-45x+710 | | .9y-.4y=6.5 | | 6(x+2)+4(3-x)=5 | | K^2+4K-70=0 | | 22y^2-184y-90=-6y^2-6 | | 9i-1=26 | | 100(1.5)(1.5)(1.5)(1.5)(1.5)(1.5)=g | | 7a+1=8a-(a-1) | | 100(1.5)(1.5)(1.5)(1.5)(1.5)=g | | 3x^-9*2x^5/x^-4 | | -x/18=6 | | 100(1.5)(1.5)(1.5)(1.5)=g | | 100(1.5)(1.5)(1.5)=g | | V^2-20v-94=0 | | 6m-m=2(m+9) | | 3(x-2)=8x-6 | | -21=3-6a | | a^2-24=5a | | 100(1.5)(1.5)=g | | 1.66*125= | | X^2-20x-94=0 | | 100(1.5)=g |

Equations solver categories