4x^2-21x+21=0

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


Simplifying
4x2 + -21x + 21 = 0

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

Solving
21 + -21x + 4x2 = 0

Solving for variable 'x'.

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

Divide each side by '4'.
5.25 + -5.25x + x2 = 0

Move the constant term to the right:

Add '-5.25' to each side of the equation.
5.25 + -5.25x + -5.25 + x2 = 0 + -5.25

Reorder the terms:
5.25 + -5.25 + -5.25x + x2 = 0 + -5.25

Combine like terms: 5.25 + -5.25 = 0.00
0.00 + -5.25x + x2 = 0 + -5.25
-5.25x + x2 = 0 + -5.25

Combine like terms: 0 + -5.25 = -5.25
-5.25x + x2 = -5.25

The x term is -5.25x.  Take half its coefficient (-2.625).
Square it (6.890625) and add it to both sides.

Add '6.890625' to each side of the equation.
-5.25x + 6.890625 + x2 = -5.25 + 6.890625

Reorder the terms:
6.890625 + -5.25x + x2 = -5.25 + 6.890625

Combine like terms: -5.25 + 6.890625 = 1.640625
6.890625 + -5.25x + x2 = 1.640625

Factor a perfect square on the left side:
(x + -2.625)(x + -2.625) = 1.640625

Calculate the square root of the right side: 1.280868846

Break this problem into two subproblems by setting 
(x + -2.625) equal to 1.280868846 and -1.280868846.

Subproblem 1

x + -2.625 = 1.280868846 Simplifying x + -2.625 = 1.280868846 Reorder the terms: -2.625 + x = 1.280868846 Solving -2.625 + x = 1.280868846 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.625' to each side of the equation. -2.625 + 2.625 + x = 1.280868846 + 2.625 Combine like terms: -2.625 + 2.625 = 0.000 0.000 + x = 1.280868846 + 2.625 x = 1.280868846 + 2.625 Combine like terms: 1.280868846 + 2.625 = 3.905868846 x = 3.905868846 Simplifying x = 3.905868846

Subproblem 2

x + -2.625 = -1.280868846 Simplifying x + -2.625 = -1.280868846 Reorder the terms: -2.625 + x = -1.280868846 Solving -2.625 + x = -1.280868846 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.625' to each side of the equation. -2.625 + 2.625 + x = -1.280868846 + 2.625 Combine like terms: -2.625 + 2.625 = 0.000 0.000 + x = -1.280868846 + 2.625 x = -1.280868846 + 2.625 Combine like terms: -1.280868846 + 2.625 = 1.344131154 x = 1.344131154 Simplifying x = 1.344131154

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.905868846, 1.344131154}

See similar equations:

| 9m=m^2 | | 36x^3-81x=0 | | c^2+2=3c | | 6c^3d-8c^4d+8c^2d^3+2cd=x | | x-x^5=0 | | x^2-15x=108 | | 3x-2(x-3)=11 | | 8(x-2)=3(x+8) | | y=-0.9*50+112 | | 208m^2-637n^2= | | y=-0.9*40+112 | | y=-0.9*30+112 | | 169b^2+196= | | (-10+6x)=15+(-5+3x)(5+12x) | | o=(2x+3y)(x-y) | | y=-5x^2+11 | | 3x-5=4x-2(4-x) | | 9x+14=6x+2 | | y=-0.9*20+112 | | y=-0.920+112 | | y=5a^2b^2-4ab-(2a^2b^2-5ab)+2a^3 | | (x-2)2-(3-x)2=1 | | d^2+2d-15=0 | | -4+(4x+1)=1 | | 4X=78 | | 7+3(2x-6)-3x= | | r^2+3r-54= | | -9x+7=5(7-x) | | 14x+17+7x=9+2x+8 | | t(t-3)=40 | | 14x+17+7x=9+21x+7 | | 0.30x+0.15(10)=0.15(74) |

Equations solver categories