-4x^2+21x+20=0

Simple and best practice solution for -4x^2+21x+20=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+20=0 equation:


Simplifying
-4x2 + 21x + 20 = 0

Reorder the terms:
20 + 21x + -4x2 = 0

Solving
20 + 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 + -5.25x + x2 = 0

Move the constant term to the right:

Add '5' to each side of the equation.
-5 + -5.25x + 5 + x2 = 0 + 5

Reorder the terms:
-5 + 5 + -5.25x + x2 = 0 + 5

Combine like terms: -5 + 5 = 0
0 + -5.25x + x2 = 0 + 5
-5.25x + x2 = 0 + 5

Combine like terms: 0 + 5 = 5
-5.25x + x2 = 5

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 + 6.890625

Reorder the terms:
6.890625 + -5.25x + x2 = 5 + 6.890625

Combine like terms: 5 + 6.890625 = 11.890625
6.890625 + -5.25x + x2 = 11.890625

Factor a perfect square on the left side:
(x + -2.625)(x + -2.625) = 11.890625

Calculate the square root of the right side: 3.448278556

Break this problem into two subproblems by setting 
(x + -2.625) equal to 3.448278556 and -3.448278556.

Subproblem 1

x + -2.625 = 3.448278556 Simplifying x + -2.625 = 3.448278556 Reorder the terms: -2.625 + x = 3.448278556 Solving -2.625 + x = 3.448278556 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 = 3.448278556 + 2.625 Combine like terms: -2.625 + 2.625 = 0.000 0.000 + x = 3.448278556 + 2.625 x = 3.448278556 + 2.625 Combine like terms: 3.448278556 + 2.625 = 6.073278556 x = 6.073278556 Simplifying x = 6.073278556

Subproblem 2

x + -2.625 = -3.448278556 Simplifying x + -2.625 = -3.448278556 Reorder the terms: -2.625 + x = -3.448278556 Solving -2.625 + x = -3.448278556 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 = -3.448278556 + 2.625 Combine like terms: -2.625 + 2.625 = 0.000 0.000 + x = -3.448278556 + 2.625 x = -3.448278556 + 2.625 Combine like terms: -3.448278556 + 2.625 = -0.823278556 x = -0.823278556 Simplifying x = -0.823278556

Solution

The solution to the problem is based on the solutions from the subproblems. x = {6.073278556, -0.823278556}

See similar equations:

| -8.06x=47.3122 | | 4(3x-9)=2(6x-2) | | 21x+7y=21 | | =k | | 3/7m-1/3=4/5 | | 281=2x-231 | | 7+9n=27n+1 | | -3.5y=7 | | .5(x-12)=8 | | 4x+1=-18x+24 | | 8(5a-b)-5(3b-7a)= | | (x+.5x)+(x+1.5x)=180 | | 5n-(7n+3)=7-(10n-9) | | 6x-11x=50 | | 24+3x=2x-16 | | 1.8(a+3)+5.6=29 | | 4z+8=2z | | 12-2a=8(a+4) | | P=-3x+9 | | 0.5x(2x-1)=60 | | 4x^2-15x-12=0 | | 2p/9=8 | | 0.4(b-32)=0.8b | | 70=3x+5y | | 4w-7=2w-3 | | 4/7y=16 | | 2x^2+x-1=absx | | (13x-5)+94=180 | | x+2x+3x+4x+5x=460 | | 27x^2=9x | | x+2x+3x+4x+5x=46 | | 2,236,000-177400x=3,500,000 |

Equations solver categories