3a^2-18a-21=-4

Simple and best practice solution for 3a^2-18a-21=-4 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 3a^2-18a-21=-4 equation:


Simplifying
3a2 + -18a + -21 = -4

Reorder the terms:
-21 + -18a + 3a2 = -4

Solving
-21 + -18a + 3a2 = -4

Solving for variable 'a'.

Reorder the terms:
-21 + 4 + -18a + 3a2 = -4 + 4

Combine like terms: -21 + 4 = -17
-17 + -18a + 3a2 = -4 + 4

Combine like terms: -4 + 4 = 0
-17 + -18a + 3a2 = 0

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

Divide each side by '3'.
-5.666666667 + -6a + a2 = 0

Move the constant term to the right:

Add '5.666666667' to each side of the equation.
-5.666666667 + -6a + 5.666666667 + a2 = 0 + 5.666666667

Reorder the terms:
-5.666666667 + 5.666666667 + -6a + a2 = 0 + 5.666666667

Combine like terms: -5.666666667 + 5.666666667 = 0.000000000
0.000000000 + -6a + a2 = 0 + 5.666666667
-6a + a2 = 0 + 5.666666667

Combine like terms: 0 + 5.666666667 = 5.666666667
-6a + a2 = 5.666666667

The a term is -6a.  Take half its coefficient (-3).
Square it (9) and add it to both sides.

Add '9' to each side of the equation.
-6a + 9 + a2 = 5.666666667 + 9

Reorder the terms:
9 + -6a + a2 = 5.666666667 + 9

Combine like terms: 5.666666667 + 9 = 14.666666667
9 + -6a + a2 = 14.666666667

Factor a perfect square on the left side:
(a + -3)(a + -3) = 14.666666667

Calculate the square root of the right side: 3.829708431

Break this problem into two subproblems by setting 
(a + -3) equal to 3.829708431 and -3.829708431.

Subproblem 1

a + -3 = 3.829708431 Simplifying a + -3 = 3.829708431 Reorder the terms: -3 + a = 3.829708431 Solving -3 + a = 3.829708431 Solving for variable 'a'. Move all terms containing a to the left, all other terms to the right. Add '3' to each side of the equation. -3 + 3 + a = 3.829708431 + 3 Combine like terms: -3 + 3 = 0 0 + a = 3.829708431 + 3 a = 3.829708431 + 3 Combine like terms: 3.829708431 + 3 = 6.829708431 a = 6.829708431 Simplifying a = 6.829708431

Subproblem 2

a + -3 = -3.829708431 Simplifying a + -3 = -3.829708431 Reorder the terms: -3 + a = -3.829708431 Solving -3 + a = -3.829708431 Solving for variable 'a'. Move all terms containing a to the left, all other terms to the right. Add '3' to each side of the equation. -3 + 3 + a = -3.829708431 + 3 Combine like terms: -3 + 3 = 0 0 + a = -3.829708431 + 3 a = -3.829708431 + 3 Combine like terms: -3.829708431 + 3 = -0.829708431 a = -0.829708431 Simplifying a = -0.829708431

Solution

The solution to the problem is based on the solutions from the subproblems. a = {6.829708431, -0.829708431}

See similar equations:

| 2x^2-15x=50 | | -2y=6-8x | | 3+6+4y-7=-8 | | 0=4x^2-12 | | 8-16k-6k^2=0 | | 3.2x-12=8 | | 2x/7-1=5 | | n^2-16n+94=7 | | 9m^2-4/25 | | x-5(x+4)=2 | | v^2+8v+16= | | 2(x+1)+2(x+1)= | | 10(z+2)-3(z-3)=4(z-2)+2(z-4) | | 900-x=300+x | | 15x-2=10x+35 | | x^2-82x=0 | | (2+l)(1+w)=24.75 | | 3(a^2-3a-10)=0 | | 3x-2x-4=8 | | 2x^4-8x^4=0 | | 3a+a=168 | | 13+2x=97 | | 7g+h=42 | | -x^2-3x+4=o | | -2n^2-9n+11=-4n^2+1 | | -x^2+3x+4=o | | 0.3x-.9=.3 | | 5.12(x)+12.42(45-x)=500 | | 6(x-2)=323 | | 2x^3+3x^2-13x+6=0 | | 12r=8+2(5r+3) | | 4(3x-9)-4=4(x-4)+32 |

Equations solver categories