-r(4r-8)=-36

Simple and best practice solution for -r(4r-8)=-36 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(4r-8)=-36 equation:


Simplifying
-1r(4r + -8) = -36

Reorder the terms:
-1r(-8 + 4r) = -36
(-8 * -1r + 4r * -1r) = -36
(8r + -4r2) = -36

Solving
8r + -4r2 = -36

Solving for variable 'r'.

Reorder the terms:
36 + 8r + -4r2 = -36 + 36

Combine like terms: -36 + 36 = 0
36 + 8r + -4r2 = 0

Factor out the Greatest Common Factor (GCF), '4'.
4(9 + 2r + -1r2) = 0

Ignore the factor 4.

Subproblem 1
Set the factor '(9 + 2r + -1r2)' equal to zero and attempt to solve:

Simplifying
9 + 2r + -1r2 = 0

Solving
9 + 2r + -1r2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-9 + -2r + r2 = 0

Move the constant term to the right:

Add '9' to each side of the equation.
-9 + -2r + 9 + r2 = 0 + 9

Reorder the terms:
-9 + 9 + -2r + r2 = 0 + 9

Combine like terms: -9 + 9 = 0
0 + -2r + r2 = 0 + 9
-2r + r2 = 0 + 9

Combine like terms: 0 + 9 = 9
-2r + r2 = 9

The r term is -2r.  Take half its coefficient (-1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
-2r + 1 + r2 = 9 + 1

Reorder the terms:
1 + -2r + r2 = 9 + 1

Combine like terms: 9 + 1 = 10
1 + -2r + r2 = 10

Factor a perfect square on the left side:
(r + -1)(r + -1) = 10

Calculate the square root of the right side: 3.16227766

Break this problem into two subproblems by setting 
(r + -1) equal to 3.16227766 and -3.16227766.


Subproblem 1
r + -1 = 3.16227766

Simplifying
r + -1 = 3.16227766

Reorder the terms:
-1 + r = 3.16227766

Solving
-1 + r = 3.16227766

Solving for variable 'r'.

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

Add '1' to each side of the equation.
-1 + 1 + r = 3.16227766 + 1

Combine like terms: -1 + 1 = 0
0 + r = 3.16227766 + 1
r = 3.16227766 + 1

Combine like terms: 3.16227766 + 1 = 4.16227766
r = 4.16227766

Simplifying
r = 4.16227766


Subproblem 2
r + -1 = -3.16227766

Simplifying
r + -1 = -3.16227766

Reorder the terms:
-1 + r = -3.16227766

Solving
-1 + r = -3.16227766

Solving for variable 'r'.

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

Add '1' to each side of the equation.
-1 + 1 + r = -3.16227766 + 1

Combine like terms: -1 + 1 = 0
0 + r = -3.16227766 + 1
r = -3.16227766 + 1

Combine like terms: -3.16227766 + 1 = -2.16227766
r = -2.16227766

Simplifying
r = -2.16227766


Solution
The solution to the problem is based on the solutions
from the subproblems.
r = {4.16227766, -2.16227766}
Solution
r = {4.16227766, -2.16227766}

See similar equations:

| -5y+20+7x=0 | | 2/5(r-2)=3/20(r-4) | | 4(48-1.75)+7y-12=180 | | -3/2(s-2)=-72 | | -8x-7=2x+23 | | 8x^2+36x+16= | | -3(x-3)-3x=5-6(x+5) | | 7x^2-18=-39x | | 7s-8=2+2s | | 23=7x-26 | | 1/2a+22/3=-1/4 | | X^5-9=aforx | | 8(q+7)=-20 | | x^3-3x-3=0 | | =7x-2 | | x-1/2=10 | | 9t-11=-15+7t | | 3/10+10x=1 | | k+10+3x=90 | | 3/10+x=10 | | (8-b)(3)+6b+12-10b= | | -3.6=-9.2p+2.2(p-3) | | (4X-9X-2)-(8X-13)= | | 3[29-(9+6)]-4*7= | | D=34-c | | 3x+7-7=12-7 | | m+3/2=-4 | | .05x+0.03=0.03x | | 7x^2=-39x-20 | | 5(p+8)+7=4(5+8p) | | 5n-7=2n+2 | | y=3B(x) |

Equations solver categories