If it's not what You are looking for type in the equation solver your own equation and let us solve it.
D( x )
x = 0
1/x <= 0
5*x-21 <= 0
x-5 <= 0
x = 0
x = 0
1/x <= 0
1/x <= 0
1*x^-1 <= 0
1*x^-1 <= 0 // : 1
x^-1 <= 0/1
x^-1 <= 0
1/(x^1) <= 0
x <> 0
1/(x^1) <= 0 // * x^2
(x^2)/(x^1) <= 0
x^1 <= 0
x <= 0
x in (-oo:0)
5*x-21 <= 0
5*x-21 <= 0
5*x-21 <= 0 // + 21
5*x <= 21 // : 5
x <= 21/5
x-5 <= 0
x-5 <= 0
x-5 <= 0 // + 5
x <= 5
x in (5:+oo)
ln(x-5)-ln(5*x-21) = ln(1/x) // - ln(1/x)
ln(x-5)-ln(5*x-21)-ln(1/x) = 0
ln(1*(x-5))-ln(5*x-21)-ln(1/x) = 0
ln((1*(x-5))/(5*x-21))-ln(1/x) = 0
ln(((1*(x-5))/(5*x-21))/(1/x)) = 0
ln(((x-5)/(5*x-21))/(1/x)) = 0
ln(((x-5)/(5*x-21))/(1/x)) = ln(e^0)
((x-5)/(5*x-21))/(1/x) = e^0
((x-5)/(5*x-21))/(1/x)-e^0 = 0
(x-5)/(x^-1*(5*x-21))-1 = 0
(x-5)/(x^-1*(5*x-21))+(-1*x^-1*(5*x-21))/(x^-1*(5*x-21)) = 0
x-1*x^-1*(5*x-21)-5 = 0
x+21*x^-1-10 = 0
x+21*x^-1-10 = 0
1*x^1+21*x^-1-10*x^0 = 0
(1*x^2-10*x^1+21*x^0)/(x^1) = 0 // * x^2
x^1*(1*x^2-10*x^1+21*x^0) = 0
x^1
x^2-10*x+21 = 0
x^2-10*x+21 = 0
DELTA = (-10)^2-(1*4*21)
DELTA = 16
DELTA > 0
x = (16^(1/2)+10)/(1*2) or x = (10-16^(1/2))/(1*2)
x = 7 or x = 3
x in { 3, 7}
(x-3)*(x-7) = 0
((x-3)*(x-7))/(x^-1*(5*x-21)) = 0
((x-3)*(x-7))/(x^-1*(5*x-21)) = 0 // * x^-1*(5*x-21)
(x-3)*(x-7) = 0
( x-3 )
x-3 = 0 // + 3
x = 3
( x-7 )
x-7 = 0 // + 7
x = 7
x in { 3}
x = 7
| 9x+5=4x-10 | | -7/17x=-9 | | 52x+3=60 | | m/2+5+11 | | 6(2x)=12 | | 7x-14=6x+3 | | -3/19x=-2 | | 5y+3+5=17 | | ex+4=10 | | -2-9x=11 | | X+(x-1)+(x+1)=351 | | 13x=29y-19 | | h=4.9t^2+120t | | X+(x+1)+(x+2)=351 | | (4w+1/5)^2 | | L=1200x35/2 | | 24x^2-25=-x^4 | | -2x+5=2-(5-2x) | | 3/4t=16 | | 3t+7= | | 5x^2+2x-4=2x^2+2x+8 | | 2(9x+15)8+2x= | | 5x+2x=6+8 | | -3x-5y=-8 | | -4=3x+1 | | x^3-x^2-5x+5=0 | | 63-2x=7x+22 | | 3/4x=-21 | | 5t(3t+7)= | | 9X/8+15/16=-1/8 | | 1/2x+1/3=10 | | 50-4x(2+5)= |