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)
2/x-(1/y) = 4 // - 4
2/x-(1/y)-4 = 0
2/x-y^-1-4 = 0
2*x^-1 = -(-y^-1-4) // : 2
x^-1 = (y^-1+4)/2
-1 < 0
1/(x^1) = (y^-1+4)/2 // * x^1
1 = x^1*((y^-1+4)/2) // : (y^-1+4)/2
2*(y^-1+4)^-1 = x^1
x = 2*(y^-1+4)^-1
x = 2*(y^-1+4)^-1
| (8*40)+(a*12)=440 | | -2x=162 | | (7x^2+5x-9)-(2x^2+3x-7)= | | 5m+4+2m=15-4m | | (9+4)(9-6)= | | 12x=-64 | | (8m+3m)-(6m-8+6m)= | | (a*8)+(a*12)=440 | | 10/12=x/10 | | 25.748=2*3.14*r^2+2*3.14*r*13 | | 15-3(5x^2-3)= | | H=2.59(45)+47.24 | | 11k-9k=14 | | H(f)=2.59(45)+47.24 | | 6x-8y=100 | | -3+6m=-15 | | 9x-18=x+22 | | X*45+200=300 | | 10x^(5/3) | | 8(1-5x)=48 | | h(1)=x^4+4x^2+8 | | 5-6y=4 | | 2r+3s-t=-3 | | 2000=F.80/3,6 | | 3y-3x=-18 | | 7x+2y=6x-5y | | Kr^2=80 | | r-2s+t=2 | | 5e^3x-1=20 | | e^7x+6=5 | | 1x^2+2x-6=0 | | H(45)=2.59(45)+47.24 |