y^2+18y-81=0

Simple and best practice solution for y^2+18y-81=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 y^2+18y-81=0 equation:


Simplifying
y2 + 18y + -81 = 0

Reorder the terms:
-81 + 18y + y2 = 0

Solving
-81 + 18y + y2 = 0

Solving for variable 'y'.

Begin completing the square.

Move the constant term to the right:

Add '81' to each side of the equation.
-81 + 18y + 81 + y2 = 0 + 81

Reorder the terms:
-81 + 81 + 18y + y2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + 18y + y2 = 0 + 81
18y + y2 = 0 + 81

Combine like terms: 0 + 81 = 81
18y + y2 = 81

The y term is 18y.  Take half its coefficient (9).
Square it (81) and add it to both sides.

Add '81' to each side of the equation.
18y + 81 + y2 = 81 + 81

Reorder the terms:
81 + 18y + y2 = 81 + 81

Combine like terms: 81 + 81 = 162
81 + 18y + y2 = 162

Factor a perfect square on the left side:
(y + 9)(y + 9) = 162

Calculate the square root of the right side: 12.727922061

Break this problem into two subproblems by setting 
(y + 9) equal to 12.727922061 and -12.727922061.

Subproblem 1

y + 9 = 12.727922061 Simplifying y + 9 = 12.727922061 Reorder the terms: 9 + y = 12.727922061 Solving 9 + y = 12.727922061 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + y = 12.727922061 + -9 Combine like terms: 9 + -9 = 0 0 + y = 12.727922061 + -9 y = 12.727922061 + -9 Combine like terms: 12.727922061 + -9 = 3.727922061 y = 3.727922061 Simplifying y = 3.727922061

Subproblem 2

y + 9 = -12.727922061 Simplifying y + 9 = -12.727922061 Reorder the terms: 9 + y = -12.727922061 Solving 9 + y = -12.727922061 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + y = -12.727922061 + -9 Combine like terms: 9 + -9 = 0 0 + y = -12.727922061 + -9 y = -12.727922061 + -9 Combine like terms: -12.727922061 + -9 = -21.727922061 y = -21.727922061 Simplifying y = -21.727922061

Solution

The solution to the problem is based on the solutions from the subproblems. y = {3.727922061, -21.727922061}

See similar equations:

| 12/15=x/32 | | x/14=12/7 | | 6/7t=48 | | (((x-5)/5)-1)=((x-13)/6) | | 11-3x=-6x+2 | | 3z+7=z+10 | | cot(x)=2.4 | | log(8)(k-8)=2 | | x^3-x^2+15*x+17=0 | | V=Bcy | | 4sin(2x)+2=0 | | 0.2x+4.4=3.3 | | (1128*2)+(120*3)=x+(x*0.2) | | -2(a-6)=-36 | | z=0.06-50/6 | | 70(-8/5) | | 2y+3=33 | | x^2-4x+4+x^2-18x+81=x^2 | | 6(c+2)-x=4(x+4)+7 | | 6-6n+3n=42-84 | | ab-9a+b-45= | | -20/-4= | | 6-6n+3n=42-8 | | 5-97-09= | | 7x^2+27x+18=0 | | 4(n+6)+4n=8+8(2n+6) | | 2e^5x=6e^4x | | -3(4s-4)-12=-2(9s+1)-2 | | 52=9x+2 | | 49=6x+1 | | 16=10b | | 8x+15=12x+3 |

Equations solver categories