x^2+7x+12=21

Simple and best practice solution for x^2+7x+12=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 x^2+7x+12=21 equation:


Simplifying
x2 + 7x + 12 = 21

Reorder the terms:
12 + 7x + x2 = 21

Solving
12 + 7x + x2 = 21

Solving for variable 'x'.

Reorder the terms:
12 + -21 + 7x + x2 = 21 + -21

Combine like terms: 12 + -21 = -9
-9 + 7x + x2 = 21 + -21

Combine like terms: 21 + -21 = 0
-9 + 7x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '9' to each side of the equation.
-9 + 7x + 9 + x2 = 0 + 9

Reorder the terms:
-9 + 9 + 7x + x2 = 0 + 9

Combine like terms: -9 + 9 = 0
0 + 7x + x2 = 0 + 9
7x + x2 = 0 + 9

Combine like terms: 0 + 9 = 9
7x + x2 = 9

The x term is 7x.  Take half its coefficient (3.5).
Square it (12.25) and add it to both sides.

Add '12.25' to each side of the equation.
7x + 12.25 + x2 = 9 + 12.25

Reorder the terms:
12.25 + 7x + x2 = 9 + 12.25

Combine like terms: 9 + 12.25 = 21.25
12.25 + 7x + x2 = 21.25

Factor a perfect square on the left side:
(x + 3.5)(x + 3.5) = 21.25

Calculate the square root of the right side: 4.609772229

Break this problem into two subproblems by setting 
(x + 3.5) equal to 4.609772229 and -4.609772229.

Subproblem 1

x + 3.5 = 4.609772229 Simplifying x + 3.5 = 4.609772229 Reorder the terms: 3.5 + x = 4.609772229 Solving 3.5 + x = 4.609772229 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.5' to each side of the equation. 3.5 + -3.5 + x = 4.609772229 + -3.5 Combine like terms: 3.5 + -3.5 = 0.0 0.0 + x = 4.609772229 + -3.5 x = 4.609772229 + -3.5 Combine like terms: 4.609772229 + -3.5 = 1.109772229 x = 1.109772229 Simplifying x = 1.109772229

Subproblem 2

x + 3.5 = -4.609772229 Simplifying x + 3.5 = -4.609772229 Reorder the terms: 3.5 + x = -4.609772229 Solving 3.5 + x = -4.609772229 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.5' to each side of the equation. 3.5 + -3.5 + x = -4.609772229 + -3.5 Combine like terms: 3.5 + -3.5 = 0.0 0.0 + x = -4.609772229 + -3.5 x = -4.609772229 + -3.5 Combine like terms: -4.609772229 + -3.5 = -8.109772229 x = -8.109772229 Simplifying x = -8.109772229

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.109772229, -8.109772229}

See similar equations:

| c=4.95+0.10 | | 3x+8=11x | | .5(12b-8)=-28 | | 12x-36=144 | | 2x^3-12x^2-32x= | | x(1000+2x)= | | 2x^3+12x^2+32x= | | 18x-96=120 | | 1090=111x-221480 | | 62=-28-15x | | 4(s+6)=-28 | | 4n+15=63 | | H-(7.8)=4 | | U-7.5=2.5 | | -3n+2(n-5)=6 | | 6m=235 | | 4(2t+3)=3(4t+1)-5(3t-2) | | 6m=236 | | z/5+3=-35 | | 21=y+5 | | 4(2x+5)=-2(2x-16) | | -2x-8+3x=-7+2 | | 15(t+2)+pt=6 | | -11x+44=121 | | -2x-8+3x=-7+4 | | -6x+57=-69 | | 9g+9=9(g+9) | | x^2-7x+9= | | 15-5(4x-7)=40 | | J-6=6 | | -3(6p+2)-2(6-17p)=3(7+5p) | | 24xy^2-16x^2y=0 |

Equations solver categories