y^2+4y-81=0

Simple and best practice solution for y^2+4y-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+4y-81=0 equation:


Simplifying
y2 + 4y + -81 = 0

Reorder the terms:
-81 + 4y + y2 = 0

Solving
-81 + 4y + 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 + 4y + 81 + y2 = 0 + 81

Reorder the terms:
-81 + 81 + 4y + y2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + 4y + y2 = 0 + 81
4y + y2 = 0 + 81

Combine like terms: 0 + 81 = 81
4y + y2 = 81

The y term is 4y.  Take half its coefficient (2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
4y + 4 + y2 = 81 + 4

Reorder the terms:
4 + 4y + y2 = 81 + 4

Combine like terms: 81 + 4 = 85
4 + 4y + y2 = 85

Factor a perfect square on the left side:
(y + 2)(y + 2) = 85

Calculate the square root of the right side: 9.219544457

Break this problem into two subproblems by setting 
(y + 2) equal to 9.219544457 and -9.219544457.

Subproblem 1

y + 2 = 9.219544457 Simplifying y + 2 = 9.219544457 Reorder the terms: 2 + y = 9.219544457 Solving 2 + y = 9.219544457 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '-2' to each side of the equation. 2 + -2 + y = 9.219544457 + -2 Combine like terms: 2 + -2 = 0 0 + y = 9.219544457 + -2 y = 9.219544457 + -2 Combine like terms: 9.219544457 + -2 = 7.219544457 y = 7.219544457 Simplifying y = 7.219544457

Subproblem 2

y + 2 = -9.219544457 Simplifying y + 2 = -9.219544457 Reorder the terms: 2 + y = -9.219544457 Solving 2 + y = -9.219544457 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '-2' to each side of the equation. 2 + -2 + y = -9.219544457 + -2 Combine like terms: 2 + -2 = 0 0 + y = -9.219544457 + -2 y = -9.219544457 + -2 Combine like terms: -9.219544457 + -2 = -11.219544457 y = -11.219544457 Simplifying y = -11.219544457

Solution

The solution to the problem is based on the solutions from the subproblems. y = {7.219544457, -11.219544457}

See similar equations:

| 8.1b=-64.8 | | (4x+3)+(6x^2-11x-35)= | | 60(2A-6)/4B | | h=-16t^2+128t+50 | | 2w^2=162 | | ysqared+4y-81=0 | | 6x^2-8=2(3x^2-4) | | x^2-22y=-121-y^2-12x | | (4x+3)+(6x-11x-35)= | | 0=x^2+2(logx) | | -3.6c=18 | | 0=x^2+2lnx | | (4x+3)+(2x-7)(3x+5)= | | 4(2x+4)=3x+4-x | | (6x+7)(8x-7)=0 | | (-2.5)(3.25)= | | x+30+2x+45=180 | | 2x+7y=80 | | 3x-3=79 | | -5n+15=25 | | 2w^2+w-88=0 | | (10)-(2x)= | | 28+12m=132 | | N+0.08n=49.41 | | 2w^6+1w-88=0 | | 5x^3+25x^2+2x+10= | | ln(7x+9)+ln(5x)=ln(x^2) | | 2+5(m-1)=5m-(m-15) | | 4x+28=6+14x-58 | | 3=2x^2-21 | | x+5+2x=180 | | 7t+6=41 |

Equations solver categories