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+3 = 0
x = 0
x = 0
x+3 = 0
x+3 = 0
x+3 = 0 // - 3
x = -3
x in (-oo:-3) U (-3:0) U (0:+oo)
1/(x+3)+1/x = (x+4)/(x+3) // - (x+4)/(x+3)
1/(x+3)-((x+4)/(x+3))+1/x = 0
1/(x+3)+(-1*(x+4))/(x+3)+1/x = 0
(1*x)/(x*(x+3))+(-1*x*(x+4))/(x*(x+3))+(1*(x+3))/(x*(x+3)) = 0
1*(x+3)-1*x*(x+4)+1*x = 0
x-x^2-3*x+3 = 0
3-x^2-2*x = 0
3-x^2-2*x = 0
3-x^2-2*x = 0
DELTA = (-2)^2-(-1*3*4)
DELTA = 16
DELTA > 0
x = (16^(1/2)+2)/(-1*2) or x = (2-16^(1/2))/(-1*2)
x = -3 or x = 1
(x+3)*(x-1) = 0
((x+3)*(x-1))/(x*(x+3)) = 0
((x+3)*(x-1))/(x*(x+3)) = 0 // * x*(x+3)
(x+3)*(x-1) = 0
( x+3 )
x+3 = 0 // - 3
x = -3
( x-1 )
x-1 = 0 // + 1
x = 1
x in { -3}
x = 1
| 8x-6=6x+20 | | 1=t-8 | | 2x+3yi+4xi-2y-5+10i=x+y+2-(y-x-5)i | | 9(x-4)=6(x-12) | | -g+8=32 | | 6j=6j | | -2x(3x+11)(2x-5)=0 | | 15a+4/5a-13/17a=12+9a-3a | | 1/2a+3/4t+2/3a+(-1/2t) | | 7(x-8)+4=2x-7 | | 1/3x+5=13 | | 1+n=-8(-3-3n) | | 8(9x-9)+8=8 | | 80x+60y=200 | | 4x+26x+8=10 | | F(x)=x^2-3-1 | | -4x-5=-53 | | 1/2(4+6x)=1/3x+2/3(x+9) | | 2x-15=-19 | | 63x+108y=190 | | 12x^2-10=7 | | -8a=-5(a+8)-8a | | -6(1/3+2x)=-2(x-4) | | 3x-8x=20 | | -3=y-4 | | (7wz^4)(5w^5z^3)= | | 6x^2+6y^2=150 | | 10+12x+29=180 | | 3(4x+1)=x | | -2-3k=1 | | -15(-18x+21)=9(-3x+229) | | -40=-24t |