If it's not what You are looking for type in the equation solver your own equation and let us solve it.
D( n )
n = 0
n = 0
n = 0
n in (-oo:0) U (0:+oo)
7/9 = 70/n // - 70/n
7/9-(70/n) = 0
7/9-70*n^-1 = 0
-70*n^-1 = -7/9 // : -70
n^-1 = 1/90
-1 < 0
1/(n^1) = 1/90 // * n^1
1 = 1/90*n^1 // : 1/90
90 = n^1
n = 90
n = 90
| 25x(x+1)=66 | | 2x+23=4x-19 | | 3x-5x+8=0 | | Y^2-1/64=0 | | -9+38=15 | | 2(7)+y=35 | | 36=10v-v | | X^2-13-130=0 | | 8616/12= | | X-37=35-2x | | 116(3n)=500 | | 21=4u+3u | | 20+5xy+4y^2+10+y^2+xy=0 | | 116(7n)=500 | | f(x)=76+3.8x | | 7x^2-12=0 | | 6v^2+18=0 | | 14(v+4)-2v=3(4v+4)-13 | | 13v-7v=48 | | -8-3=5 | | -7(5n-6)=4+3n | | 2(6)+y=35 | | 2(x+3)+2x=x-12 | | -32=7-3x | | -18=5r-4r | | f(x)=2x^4-9x^2+7 | | 3x^2+3y^2+4y-7=0 | | 13=3+4 | | -1=-2x+x-2 | | 9/n=27/81 | | 116-n/7=500 | | 2(5)+y=34 |