x^2+21x-20=0

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


Simplifying
x2 + 21x + -20 = 0

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

Solving
-20 + 21x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '20' to each side of the equation.
-20 + 21x + 20 + x2 = 0 + 20

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

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

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

The x term is 21x.  Take half its coefficient (10.5).
Square it (110.25) and add it to both sides.

Add '110.25' to each side of the equation.
21x + 110.25 + x2 = 20 + 110.25

Reorder the terms:
110.25 + 21x + x2 = 20 + 110.25

Combine like terms: 20 + 110.25 = 130.25
110.25 + 21x + x2 = 130.25

Factor a perfect square on the left side:
(x + 10.5)(x + 10.5) = 130.25

Calculate the square root of the right side: 11.412712211

Break this problem into two subproblems by setting 
(x + 10.5) equal to 11.412712211 and -11.412712211.

Subproblem 1

x + 10.5 = 11.412712211 Simplifying x + 10.5 = 11.412712211 Reorder the terms: 10.5 + x = 11.412712211 Solving 10.5 + x = 11.412712211 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10.5' to each side of the equation. 10.5 + -10.5 + x = 11.412712211 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = 11.412712211 + -10.5 x = 11.412712211 + -10.5 Combine like terms: 11.412712211 + -10.5 = 0.912712211 x = 0.912712211 Simplifying x = 0.912712211

Subproblem 2

x + 10.5 = -11.412712211 Simplifying x + 10.5 = -11.412712211 Reorder the terms: 10.5 + x = -11.412712211 Solving 10.5 + x = -11.412712211 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10.5' to each side of the equation. 10.5 + -10.5 + x = -11.412712211 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = -11.412712211 + -10.5 x = -11.412712211 + -10.5 Combine like terms: -11.412712211 + -10.5 = -21.912712211 x = -21.912712211 Simplifying x = -21.912712211

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.912712211, -21.912712211}

See similar equations:

| 20+15=50-x | | 6-4a=a+6 | | x-8y=58 | | k/10=8/4 | | (12x-34)=180 | | 2x+x+3y=180 | | y/3-9=12 | | megan+G= | | 8x+50=12x-174 | | MEGA= | | X+5X=165 | | y=1.5*-1+6 | | 7=7x+3(5x-13) | | 6(x-2)=8x-12-2x | | y=1.5*1+6 | | 23.5+y=68.88 | | 2x+13=2(x+5) | | 64+6x=208 | | 8=12+p | | 3=-9+z | | c^2+3x+2=0 | | y=1.5*0+6 | | x-9y=65 | | y=2x+0.4 | | (38.5)(12.5)= | | 3x+y=69 | | t=c-x/x | | y+1+(-1)-(-2)=y+3-1-(-y) | | 3x/4=x-40 | | q/-8-11=7 | | 9w+5=3w-1 | | -46-3n=23 |

Equations solver categories