20x-2x^2=21

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


Simplifying
20x + -2x2 = 21

Solving
20x + -2x2 = 21

Solving for variable 'x'.

Reorder the terms:
-21 + 20x + -2x2 = 21 + -21

Combine like terms: 21 + -21 = 0
-21 + 20x + -2x2 = 0

Begin completing the square.  Divide all terms by
-2 the coefficient of the squared term: 

Divide each side by '-2'.
10.5 + -10x + x2 = 0

Move the constant term to the right:

Add '-10.5' to each side of the equation.
10.5 + -10x + -10.5 + x2 = 0 + -10.5

Reorder the terms:
10.5 + -10.5 + -10x + x2 = 0 + -10.5

Combine like terms: 10.5 + -10.5 = 0.0
0.0 + -10x + x2 = 0 + -10.5
-10x + x2 = 0 + -10.5

Combine like terms: 0 + -10.5 = -10.5
-10x + x2 = -10.5

The x term is -10x.  Take half its coefficient (-5).
Square it (25) and add it to both sides.

Add '25' to each side of the equation.
-10x + 25 + x2 = -10.5 + 25

Reorder the terms:
25 + -10x + x2 = -10.5 + 25

Combine like terms: -10.5 + 25 = 14.5
25 + -10x + x2 = 14.5

Factor a perfect square on the left side:
(x + -5)(x + -5) = 14.5

Calculate the square root of the right side: 3.807886553

Break this problem into two subproblems by setting 
(x + -5) equal to 3.807886553 and -3.807886553.

Subproblem 1

x + -5 = 3.807886553 Simplifying x + -5 = 3.807886553 Reorder the terms: -5 + x = 3.807886553 Solving -5 + x = 3.807886553 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '5' to each side of the equation. -5 + 5 + x = 3.807886553 + 5 Combine like terms: -5 + 5 = 0 0 + x = 3.807886553 + 5 x = 3.807886553 + 5 Combine like terms: 3.807886553 + 5 = 8.807886553 x = 8.807886553 Simplifying x = 8.807886553

Subproblem 2

x + -5 = -3.807886553 Simplifying x + -5 = -3.807886553 Reorder the terms: -5 + x = -3.807886553 Solving -5 + x = -3.807886553 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '5' to each side of the equation. -5 + 5 + x = -3.807886553 + 5 Combine like terms: -5 + 5 = 0 0 + x = -3.807886553 + 5 x = -3.807886553 + 5 Combine like terms: -3.807886553 + 5 = 1.192113447 x = 1.192113447 Simplifying x = 1.192113447

Solution

The solution to the problem is based on the solutions from the subproblems. x = {8.807886553, 1.192113447}

See similar equations:

| 7(x+10)-7=126-2X | | y^2+20x+2y-39=0 | | (x+1)(x+375)=750ft^2 | | 4(2x+1)=5(3x-2) | | -6(3y+8)= | | 6(6x-8)+4x=12 | | -13+3=-76 | | 6x^3-3sin(x)=0 | | 6(6x+8)+4x=12 | | 4z=8-(z+3) | | -38+8x=3x+67 | | 12x+5=0 | | 7x-9/2=13 | | 12x^2-72x+y+78=0 | | (x+1)(x+375)=750 | | 2=4x-18 | | 5n-10+1+6n= | | 6(4X-10)-4(8+8X)=14 | | 64+64+44=x | | 39+144+x=180 | | 3=2x-15 | | 3*30x= | | n(n+1)=306 | | 90-(4x+1+5x-5)=0 | | 2x^2+42x-1080=0 | | 1=32x-15 | | 36x^2-748x-2465=0 | | M=8-2p+2m | | f(x)=-2x^2-8x+1 | | 5b+10-8b= | | 11m-m^2=0 | | 3(2y+3)-4y=18 |

Equations solver categories