If it's not what You are looking for type in the equation solver your own equation and let us solve it.
D( r )
r = 0
r = 0
r = 0
r in (-oo:0) U (0:+oo)
16/30 = 8/r // - 8/r
16/30-(8/r) = 0
16/30-8*r^-1 = 0
-8*r^-1 = -8/15 // : -8
r^-1 = 1/15
-1 < 0
1/(r^1) = 1/15 // * r^1
1 = 1/15*r^1 // : 1/15
15 = r^1
r = 15
r = 15
| 2+5k=3(k-2) | | 6(x-5)=-36+6x | | 32/36=p/9 | | -.4+7d=.4 | | s+59=-s+9 | | 6x+30=-21x+21+9x | | 5(2d+4)=353 | | 2(x-7)=13+2x | | 4b+2(3-b)= | | 2x=18x+3 | | B+40+33=180 | | 8-5x+2=-15 | | 8x^3-42x-2=0 | | -6(x-6)+3x=-3x+41 | | 26=x+250 | | 3(5x-7y)= | | 9h-4=2h+3 | | (14/x^4)-(18/x^5) | | Y=15(5)-10 | | 3(p-0.75)=5.88 | | (2x-1/2)/(4/5*x^2)=5/(2x-0,5) | | 7/b=63/99 | | 6+z=48-z | | X^3+5x^2+8x+6=0 | | 4(.8y)+6(.8y)+y=180 | | -61/2n=8 | | 18x^2+12x=22 | | (17x+4)+(x+4)=49 | | 3(2x-8)=-48 | | 4x+6x+y=4x+x+5y | | X/35=4/7 | | .5g+.25g=14 |