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
x = 0
x = 0
x in (-oo:0) U (0:+oo)
3/8 > 5/x // - 5/x
3/8-(5/x) > 0
3/8-5*x^-1 > 0
-5*x^-1 > -3/8
-5*x^-1 > -3/8 // * -1
5*x^-1 < 3/8
5*x^-1 < 3/8 // : 5
x^-1 < 3/8/5
x^-1 < 3/40
1/(x^1) < 3/40
x <> 0
1/(x^1) < 3/40 // * x^2
(x^2)/(x^1) < 3/40*x^2
x^1 < 3/40*x^2
x-3/40*x^2 < 0
x^1*(1-3/40*x) < 0
x < 0
-(abs(x))^1*(3/40*(abs(x))^1+1) < 0 // : -(abs(x))^1
3/40*(abs(x))^1+1 > 0
3/40*(abs(x))^1 > -1 // : 3/40
(abs(x))^1 > -1/3/40
(abs(x))^1 > -40/3 // ^ 1/1
abs(x) > (-40/3)^(1/1)
abs(x) > -40/3
x in (-oo:0)
x < 0
x > 0
x^1*(1-(3/40*x^1)) < 0 // : x^1
1-(3/40*x^1) < 0
1 < 3/40*x^1 // : 3/40
1/3/40 < x^1 // ^ 1/1
(1/3/40)^(1/1) < x
x in (40/3:+oo)
x > 0
x in (-oo:0) U (40/3:+oo)
x in (-oo:0) U (40/3:+oo)
(-oo:0) U (40/3:+oo)
| -18+X-21=72 | | 3+9(1+6f)=35 | | -18+21-X=72 | | 4x+10=6x-3 | | 33+9v=-8(6v-7) | | 16x(3/11) | | Log[2]35x-log[2]7=3 | | 28=6+5(z-2) | | 15=7/10y | | 13a-15b+2a= | | 3(6-7c)=-31 | | D^2+16=0 | | 22500/20 | | pq=21-0.5q | | x=21-0.5q | | x^2+6x+8y-23=0 | | x^2-10xy+y^2=12 | | a/3-1/3=-5 | | (8/3)x-16 | | 3x^2=(2x)(2x+10) | | (2ln5-ln7)/(2ln-3ln5) | | 2ln5-ln7/2ln7-3ln5 | | 2(t+5)(t-8)=0 | | -7y+9+3=33 | | 2x^5-5x^4+5=0 | | 2n^2+10n+11=0 | | 20e^2x=75e^3x | | 14x^2-18x-2996=0 | | 6+x+5=6+x+5 | | 2x-1=-x+4 | | x^2-2.414*x=1.8 | | 10x^2-13x-1130=0 |