If it's not what You are looking for type in the equation solver your own equation and let us solve it.
D( x )
8*x+72 = 0
x^2-81 = 0
(6*x-24)/(8*x+72) = 0
8*x+72 = 0
8*x+72 = 0
8*x+72 = 0 // - 72
8*x = -72 // : 8
x = -72/8
x = -9
x^2-81 = 0
x^2-81 = 0
1*x^2 = 81 // : 1
x^2 = 81
x^2 = 81 // ^ 1/2
abs(x) = 9
x = 9 or x = -9
(6*x-24)/(8*x+72) = 0
(6*x-24)/(8*x+72) = 0
6*x-24 = 0 // + 24
6*x = 24 // : 6
x = 24/6
x = 4
x in (-oo:-9) U (-9:4) U (4:9) U (9:+oo)
((5*x)/(x^2-81))/((6*x-24)/(8*x+72)) = x // - x
((5*x)/(x^2-81))/((6*x-24)/(8*x+72))-x = 0
(5*x*(8*x+72))/((x^2-81)*(6*x-24))-x = 0
(5*x*(8*x+72))/((x^2-81)*(6*x-24))+(-x*(x^2-81)*(6*x-24))/((x^2-81)*(6*x-24)) = 0
5*x*(8*x+72)-x*(x^2-81)*(6*x-24) = 0
24*x^3-6*x^4+526*x^2-1584*x = 0
24*x^3-6*x^4+526*x^2-1584*x = 0
2*x*(12*x^2-3*x^3+263*x-792) = 0
12*x^2-3*x^3+263*x-792 = 0
{ 1, -1, 2, -2, 3, -3, 4, -4, 6, -6, 8, -8, 9, -9, 11, -11, 12, -12, 18, -18, 22, -22, 24, -24, 33, -33, 36, -36, 44, -44, 66, -66, 72, -72, 88, -88, 99, -99, 132, -132, 198, -198, 264, -264, 396, -396, 792, -792 }
1
x = 1
12*x^2-3*x^3+263*x-792 = -520
1
-1
x = -1
12*x^2-3*x^3+263*x-792 = -1040
-1
2
x = 2
12*x^2-3*x^3+263*x-792 = -242
2
-2
x = -2
12*x^2-3*x^3+263*x-792 = -1246
-2
3
x = 3
12*x^2-3*x^3+263*x-792 = 24
3
-3
x = -3
12*x^2-3*x^3+263*x-792 = -1392
-3
4
x = 4
12*x^2-3*x^3+263*x-792 = 260
4
-4
x = -4
12*x^2-3*x^3+263*x-792 = -1460
-4
6
x = 6
12*x^2-3*x^3+263*x-792 = 570
6
-6
x = -6
12*x^2-3*x^3+263*x-792 = -1290
-6
8
x = 8
12*x^2-3*x^3+263*x-792 = 544
8
-8
x = -8
12*x^2-3*x^3+263*x-792 = -592
-8
9
x = 9
12*x^2-3*x^3+263*x-792 = 360
9
-9
x = -9
12*x^2-3*x^3+263*x-792 = 0
-9
x+9
39*x-3*x^2-88
12*x^2-3*x^3+263*x-792
x+9
3*x^3+27*x^2
39*x^2+263*x-792
-39*x^2-351*x
-88*x-792
88*x+792
0
39*x-3*x^2-88 = 0
DELTA = 39^2-(-88*(-3)*4)
DELTA = 465
DELTA > 0
x = (465^(1/2)-39)/(-3*2) or x = (-465^(1/2)-39)/(-3*2)
x = (465^(1/2)-39)/(-6) or x = (465^(1/2)+39)/6
x in { (465^(1/2)-39)/(-6), (465^(1/2)+39)/6, -9}
2*x*(x-((465^(1/2)-39)/(-6)))*(x-((465^(1/2)+39)/6))*(x+9) = 0
(2*x*(x-((465^(1/2)-39)/(-6)))*(x-((465^(1/2)+39)/6))*(x+9))/((x^2-81)*(6*x-24)) = 0
(2*x*(x-((465^(1/2)-39)/(-6)))*(x-((465^(1/2)+39)/6))*(x+9))/((x^2-81)*(6*x-24)) = 0 // * (x^2-81)*(6*x-24)
2*x*(x-((465^(1/2)-39)/(-6)))*(x-((465^(1/2)+39)/6))*(x+9) = 0
( 2*x )
2*x = 0 // : 2
x = 0
( x+9 )
x+9 = 0 // - 9
x = -9
( x-((465^(1/2)+39)/6) )
x-((465^(1/2)+39)/6) = 0 // + (465^(1/2)+39)/6
x = (465^(1/2)+39)/6
( x-((465^(1/2)-39)/(-6)) )
x-((465^(1/2)-39)/(-6)) = 0 // + (465^(1/2)-39)/(-6)
x = (465^(1/2)-39)/(-6)
x in { -9}
x in { 0, (465^(1/2)+39)/6, (465^(1/2)-39)/(-6) }
| 1.8-16.3=1.9y+13.3 | | 3x+6=2-x+3x | | 6y-9-2y=2y-1 | | 3ax-5=2x+3 | | -6(5x+2)=199 | | -22/12 | | 5x+2=3x+36 | | 3x+7y=z | | 8=2y+10x | | 7+2x-4=6x+4-3x | | 3x+6=2-x+3 | | -25v+105=-9v-18 | | X+12=6x-20 | | -3x+8+4x=6+x+2 | | 6x-11=20y+19 | | A-18=26 | | 1.8y-16.3=-1.9+13.3 | | 7y+8=16-3y | | -2/5+1/2x=1/3 | | -10/21x+3/7=8/21 | | 10+A=23 | | 49m^2-n^2=0 | | 2(-x-3)=-36-7x | | 8(c+4)=8(c-2) | | 43=-10n+26 | | 6(x-2)/3=4(x-2)/12 | | 15-a=10 | | -y=85 | | 7x-3x+8=2x-2 | | 48p-5=-5-5 | | 6(x+6)+2=6x+4 | | 4x^2-28x+49/2x-7x=-2 |