3.5x+x^2=81

Simple and best practice solution for 3.5x+x^2=81 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 3.5x+x^2=81 equation:


Simplifying
3.5x + x2 = 81

Solving
3.5x + x2 = 81

Solving for variable 'x'.

Reorder the terms:
-81 + 3.5x + x2 = 81 + -81

Combine like terms: 81 + -81 = 0
-81 + 3.5x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '81' to each side of the equation.
-81 + 3.5x + 81 + x2 = 0 + 81

Reorder the terms:
-81 + 81 + 3.5x + x2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + 3.5x + x2 = 0 + 81
3.5x + x2 = 0 + 81

Combine like terms: 0 + 81 = 81
3.5x + x2 = 81

The x term is 3.5x.  Take half its coefficient (1.75).
Square it (3.0625) and add it to both sides.

Add '3.0625' to each side of the equation.
3.5x + 3.0625 + x2 = 81 + 3.0625

Reorder the terms:
3.0625 + 3.5x + x2 = 81 + 3.0625

Combine like terms: 81 + 3.0625 = 84.0625
3.0625 + 3.5x + x2 = 84.0625

Factor a perfect square on the left side:
(x + 1.75)(x + 1.75) = 84.0625

Calculate the square root of the right side: 9.16856041

Break this problem into two subproblems by setting 
(x + 1.75) equal to 9.16856041 and -9.16856041.

Subproblem 1

x + 1.75 = 9.16856041 Simplifying x + 1.75 = 9.16856041 Reorder the terms: 1.75 + x = 9.16856041 Solving 1.75 + x = 9.16856041 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.75' to each side of the equation. 1.75 + -1.75 + x = 9.16856041 + -1.75 Combine like terms: 1.75 + -1.75 = 0.00 0.00 + x = 9.16856041 + -1.75 x = 9.16856041 + -1.75 Combine like terms: 9.16856041 + -1.75 = 7.41856041 x = 7.41856041 Simplifying x = 7.41856041

Subproblem 2

x + 1.75 = -9.16856041 Simplifying x + 1.75 = -9.16856041 Reorder the terms: 1.75 + x = -9.16856041 Solving 1.75 + x = -9.16856041 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.75' to each side of the equation. 1.75 + -1.75 + x = -9.16856041 + -1.75 Combine like terms: 1.75 + -1.75 = 0.00 0.00 + x = -9.16856041 + -1.75 x = -9.16856041 + -1.75 Combine like terms: -9.16856041 + -1.75 = -10.91856041 x = -10.91856041 Simplifying x = -10.91856041

Solution

The solution to the problem is based on the solutions from the subproblems. x = {7.41856041, -10.91856041}

See similar equations:

| -5+3+7-2(40)= | | log(x+5)-log(4-x)+log(3x-1)=log(3x-1)-log(x+4) | | U^2=-4 | | 2x+(x+39)=90 | | 7x^2+7=-103 | | 3x-5=log(2)(256) | | 4[80+b]-12ifb=20 | | 4(x-2)=15-x | | -x^2=8x+20 | | -3(x+3)-8=5 | | (x-9)+8x=180 | | Y=2cos^2x-2sen^2x | | 4sec^2(x)=0 | | 5x-34=2x-4 | | a/9.05=5.3 | | R^2-2.5-21=0 | | C(x)=15.00+0.20x | | (4x-3)square-(2x+3)(4x-1)= | | -10t^2+60t=h(t) | | 2x+(x+33)=180 | | 3x-6=w | | x+5=log(4)1024 | | welcx+79=2x-37 | | x+23+x+154=180 | | 52=18x-2 | | 28x-36=factor | | 2b-4+3b-6=4-3+2 | | 2x^2+bx-2=0 | | 5x+3y=560 | | Cos(2x)cos(4x)= | | n+-8=-15 | | 170+0.25x=370 |

Equations solver categories