a^2+12a-21=0

Simple and best practice solution for a^2+12a-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 a^2+12a-21=0 equation:


Simplifying
a2 + 12a + -21 = 0

Reorder the terms:
-21 + 12a + a2 = 0

Solving
-21 + 12a + a2 = 0

Solving for variable 'a'.

Begin completing the square.

Move the constant term to the right:

Add '21' to each side of the equation.
-21 + 12a + 21 + a2 = 0 + 21

Reorder the terms:
-21 + 21 + 12a + a2 = 0 + 21

Combine like terms: -21 + 21 = 0
0 + 12a + a2 = 0 + 21
12a + a2 = 0 + 21

Combine like terms: 0 + 21 = 21
12a + a2 = 21

The a term is 12a.  Take half its coefficient (6).
Square it (36) and add it to both sides.

Add '36' to each side of the equation.
12a + 36 + a2 = 21 + 36

Reorder the terms:
36 + 12a + a2 = 21 + 36

Combine like terms: 21 + 36 = 57
36 + 12a + a2 = 57

Factor a perfect square on the left side:
(a + 6)(a + 6) = 57

Calculate the square root of the right side: 7.549834435

Break this problem into two subproblems by setting 
(a + 6) equal to 7.549834435 and -7.549834435.

Subproblem 1

a + 6 = 7.549834435 Simplifying a + 6 = 7.549834435 Reorder the terms: 6 + a = 7.549834435 Solving 6 + a = 7.549834435 Solving for variable 'a'. Move all terms containing a to the left, all other terms to the right. Add '-6' to each side of the equation. 6 + -6 + a = 7.549834435 + -6 Combine like terms: 6 + -6 = 0 0 + a = 7.549834435 + -6 a = 7.549834435 + -6 Combine like terms: 7.549834435 + -6 = 1.549834435 a = 1.549834435 Simplifying a = 1.549834435

Subproblem 2

a + 6 = -7.549834435 Simplifying a + 6 = -7.549834435 Reorder the terms: 6 + a = -7.549834435 Solving 6 + a = -7.549834435 Solving for variable 'a'. Move all terms containing a to the left, all other terms to the right. Add '-6' to each side of the equation. 6 + -6 + a = -7.549834435 + -6 Combine like terms: 6 + -6 = 0 0 + a = -7.549834435 + -6 a = -7.549834435 + -6 Combine like terms: -7.549834435 + -6 = -13.549834435 a = -13.549834435 Simplifying a = -13.549834435

Solution

The solution to the problem is based on the solutions from the subproblems. a = {1.549834435, -13.549834435}

See similar equations:

| X+(11)=13 | | 3b-5=-44 | | 42x^2-18x= | | ln(5+3)=ln(5)+ln(3) | | E-14=0 | | 21=b-6 | | c+7=9 | | y=20(.682) | | y=20(1.025) | | a+4=35 | | 8(1-3x)=7(3x-1) | | x^2-mx-(m^2-5)=0 | | 4y-9=11y-23 | | (5-2i)-(3+3i)= | | y=95+15x | | -x+b=2 | | 4x-5x-7=3x+10 | | Y-0.7-5.1=1.8(y+3) | | 5x+15+7x-11=360 | | 3r+3s+2t=-9 | | 5x+15+x-11=360 | | 5x+2x+10=3x+42 | | 1.33y-.5=1.6 | | 2+15=9 | | 2x^2+7x-6=x^2+4x+4 | | 8x-26-26=4x-13-x | | 4x+19=-96x | | 5e-10+7=22 | | 7x-18=4x+18 | | -3+7=x-1 | | y=-9x+-4 | | X-1*4=3*4 |

Equations solver categories