18x^2+4x=21

Simple and best practice solution for 18x^2+4x=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 18x^2+4x=21 equation:


Simplifying
18x2 + 4x = 21

Reorder the terms:
4x + 18x2 = 21

Solving
4x + 18x2 = 21

Solving for variable 'x'.

Reorder the terms:
-21 + 4x + 18x2 = 21 + -21

Combine like terms: 21 + -21 = 0
-21 + 4x + 18x2 = 0

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

Divide each side by '18'.
-1.166666667 + 0.2222222222x + x2 = 0

Move the constant term to the right:

Add '1.166666667' to each side of the equation.
-1.166666667 + 0.2222222222x + 1.166666667 + x2 = 0 + 1.166666667

Reorder the terms:
-1.166666667 + 1.166666667 + 0.2222222222x + x2 = 0 + 1.166666667

Combine like terms: -1.166666667 + 1.166666667 = 0.000000000
0.000000000 + 0.2222222222x + x2 = 0 + 1.166666667
0.2222222222x + x2 = 0 + 1.166666667

Combine like terms: 0 + 1.166666667 = 1.166666667
0.2222222222x + x2 = 1.166666667

The x term is 0.2222222222x.  Take half its coefficient (0.1111111111).
Square it (0.01234567901) and add it to both sides.

Add '0.01234567901' to each side of the equation.
0.2222222222x + 0.01234567901 + x2 = 1.166666667 + 0.01234567901

Reorder the terms:
0.01234567901 + 0.2222222222x + x2 = 1.166666667 + 0.01234567901

Combine like terms: 1.166666667 + 0.01234567901 = 1.17901234601
0.01234567901 + 0.2222222222x + x2 = 1.17901234601

Factor a perfect square on the left side:
(x + 0.1111111111)(x + 0.1111111111) = 1.17901234601

Calculate the square root of the right side: 1.085823349

Break this problem into two subproblems by setting 
(x + 0.1111111111) equal to 1.085823349 and -1.085823349.

Subproblem 1

x + 0.1111111111 = 1.085823349 Simplifying x + 0.1111111111 = 1.085823349 Reorder the terms: 0.1111111111 + x = 1.085823349 Solving 0.1111111111 + x = 1.085823349 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.1111111111' to each side of the equation. 0.1111111111 + -0.1111111111 + x = 1.085823349 + -0.1111111111 Combine like terms: 0.1111111111 + -0.1111111111 = 0.0000000000 0.0000000000 + x = 1.085823349 + -0.1111111111 x = 1.085823349 + -0.1111111111 Combine like terms: 1.085823349 + -0.1111111111 = 0.9747122379 x = 0.9747122379 Simplifying x = 0.9747122379

Subproblem 2

x + 0.1111111111 = -1.085823349 Simplifying x + 0.1111111111 = -1.085823349 Reorder the terms: 0.1111111111 + x = -1.085823349 Solving 0.1111111111 + x = -1.085823349 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.1111111111' to each side of the equation. 0.1111111111 + -0.1111111111 + x = -1.085823349 + -0.1111111111 Combine like terms: 0.1111111111 + -0.1111111111 = 0.0000000000 0.0000000000 + x = -1.085823349 + -0.1111111111 x = -1.085823349 + -0.1111111111 Combine like terms: -1.085823349 + -0.1111111111 = -1.1969344601 x = -1.1969344601 Simplifying x = -1.1969344601

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.9747122379, -1.1969344601}

See similar equations:

| 149=9x-31 | | 141=12x+9 | | 51=4x+7 | | =x^2-11x+30 | | 7t-4=5t | | 158+x/3=75 | | 8d+3=6d+4 | | 14a=-42 | | =y^4-9y^2+20 | | -12a=-132 | | .16a=17 | | x/10=80/100 | | 3x^2-18y=0 | | 4x-1=2x+11 | | x/22.5=85/100 | | 5x+10=-3x+2 | | =x^4-10x^2+9 | | 3(x-4)=-18 | | x/10=77/100 | | 6p=5p-3 | | .28q=-4 | | 4x-3y=-7x+9y | | 4x-3y=-7x | | =x^2+6xy+9y^2-16 | | 31=-.16n | | 4n-18=22 | | .20x+5=12 | | ln(4x)=4 | | 2(E+7)-5=3(E+1)-1 | | x/22.5=63/100 | | x/22.5=56/100 | | (4/5)x-(1/4)x+6=(7/10)x |

Equations solver categories