r^2-3r-81=7

Simple and best practice solution for r^2-3r-81=7 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^2-3r-81=7 equation: 


Simplifying
r2 + -3r + -81 = 7

Reorder the terms:
-81 + -3r + r2 = 7

Solving
-81 + -3r + r2 = 7

Solving for variable 'r'.

Reorder the terms:
-81 + -7 + -3r + r2 = 7 + -7

Combine like terms: -81 + -7 = -88
-88 + -3r + r2 = 7 + -7

Combine like terms: 7 + -7 = 0
-88 + -3r + r2 = 0

Factor a trinomial.
(-8 + -1r)(11 + -1r) = 0


Subproblem 1
Set the factor '(-8 + -1r)' equal to zero and attempt to solve:

Simplifying
-8 + -1r = 0

Solving
-8 + -1r = 0

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

Add '8' to each side of the equation.
-8 + 8 + -1r = 0 + 8

Combine like terms: -8 + 8 = 0
0 + -1r = 0 + 8
-1r = 0 + 8

Combine like terms: 0 + 8 = 8
-1r = 8

Divide each side by '-1'.
r = -8

Simplifying
r = -8

Subproblem 2
Set the factor '(11 + -1r)' equal to zero and attempt to solve:

Simplifying
11 + -1r = 0

Solving
11 + -1r = 0

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

Add '-11' to each side of the equation.
11 + -11 + -1r = 0 + -11

Combine like terms: 11 + -11 = 0
0 + -1r = 0 + -11
-1r = 0 + -11

Combine like terms: 0 + -11 = -11
-1r = -11

Divide each side by '-1'.
r = 11

Simplifying
r = 11
Solution
r = {-8, 11}

See similar equations:

| X+6+4=16 | | 4(x-2)-3=17 | | 4.97+x=11.12 | | r=c+m | | 0.25x=0.5275 | | b^2-7b-28=2 | | 5x+1=6(x-7) | | x^2+27=196 | | r^2+16r+67=12 | | 63x=6300 | | (5x+9)=(7x-9) | | 9x^2-54x-505=-10 | | W=2x+4z | | 2+7(x+5)=16 | | 9x-9x-6=-6 | | 5n^2+30n-360=0 | | -5+4y=-13 | | -6x-14=-1+8x | | 20=5b-6b+1 | | 59-11+4n=72 | | C=37.74+0.25x | | 3k^2-3k-270=0 | | d=1/2(4.8^2)4^2 | | 5+8*6+4x=69 | | -y/3=57 | | 70/(1.75×1.75) | | 81.61+x=91.51 | | f(x)=6x^3-29x^2-6x+5 | | 5x=425 | | -15=-3w | | 242+x=1021 | | 5(3x-4)=-80 |

Equations solver categories