r^2-4r-40=0

Simple and best practice solution for r^2-4r-40=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 r^2-4r-40=0 equation: 


Simplifying
r2 + -4r + -40 = 0

Reorder the terms:
-40 + -4r + r2 = 0

Solving
-40 + -4r + r2 = 0

Solving for variable 'r'.

Begin completing the square.

Move the constant term to the right:

Add '40' to each side of the equation.
-40 + -4r + 40 + r2 = 0 + 40

Reorder the terms:
-40 + 40 + -4r + r2 = 0 + 40

Combine like terms: -40 + 40 = 0
0 + -4r + r2 = 0 + 40
-4r + r2 = 0 + 40

Combine like terms: 0 + 40 = 40
-4r + r2 = 40

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

Add '4' to each side of the equation.
-4r + 4 + r2 = 40 + 4

Reorder the terms:
4 + -4r + r2 = 40 + 4

Combine like terms: 40 + 4 = 44
4 + -4r + r2 = 44

Factor a perfect square on the left side:
(r + -2)(r + -2) = 44

Calculate the square root of the right side: 6.633249581

Break this problem into two subproblems by setting 
(r + -2) equal to 6.633249581 and -6.633249581.


Subproblem 1
r + -2 = 6.633249581

Simplifying
r + -2 = 6.633249581

Reorder the terms:
-2 + r = 6.633249581

Solving
-2 + r = 6.633249581

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '2' to each side of the equation.
-2 + 2 + r = 6.633249581 + 2

Combine like terms: -2 + 2 = 0
0 + r = 6.633249581 + 2
r = 6.633249581 + 2

Combine like terms: 6.633249581 + 2 = 8.633249581
r = 8.633249581

Simplifying
r = 8.633249581


Subproblem 2
r + -2 = -6.633249581

Simplifying
r + -2 = -6.633249581

Reorder the terms:
-2 + r = -6.633249581

Solving
-2 + r = -6.633249581

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '2' to each side of the equation.
-2 + 2 + r = -6.633249581 + 2

Combine like terms: -2 + 2 = 0
0 + r = -6.633249581 + 2
r = -6.633249581 + 2

Combine like terms: -6.633249581 + 2 = -4.633249581
r = -4.633249581

Simplifying
r = -4.633249581


Solution
The solution to the problem is based on the solutions
from the subproblems.
r = {8.633249581, -4.633249581}

See similar equations:

| x*7-50=x*4-5 | | Log(1/2)^x-6 | | 2.5=2(x+3) | | 12(10)+6(x)=8(10+x) | | 8w=4800 | | log(5x^2y^3)= | | 1.3x+10x+30=2.5 | | sin(x)+cos(4x)=0 | | (3+x)2=15 | | 12(14)+5(x)=7(14+x) | | 9x-37+4x-5=110 | | -0.2+4.5= | | 15=2(x+3) | | 30t^4-40t^3=0 | | 3xy=42+a | | 7.9/n=.79 | | 4y^4*2x^6y^6*6x= | | (2x-6)(x-6)=0 | | 396-12n=3n | | a^4-37a^2+36=0 | | 35+0.75x=32+0.87x | | k=5/2x10 | | 18(n-3)-18=396 | | X^2-15x-60x=0 | | 15(n-3)-18=396 | | 8/x-3=12/2x-3 | | 12(12n+3)+12=396 | | 7+49x=28x+34 | | 3x+x^2=43 | | Y-3=7[x+1] | | ln^2x=0 | | 6y-3=23 |

Equations solver categories