If it's not what You are looking for type in the equation solver your own equation and let us solve it.
D( x )
770-x = 0
770-x = 0
770-x = 0
770-x = 0 // - 770
-x = -770 // * -1
x = 770
x in (-oo:770) U (770:+oo)
1.123 = 770/(770-x) // - 770/(770-x)
1.123-(770/(770-x)) = 0
1.123-770*(770-x)^-1 = 0
1.123-770/(770-x) = 0
(1.123*(770-x))/(770-x)-770/(770-x) = 0
1.123*(770-x)-770 = 0
94.71-1.123*x = 0
(94.71-1.123*x)/(770-x) = 0
(94.71-1.123*x)/(770-x) = 0 // * 770-x
94.71-1.123*x = 0
94.71-1.123*x = 0 // - 94.71
-1.123*x = -94.71 // : -1.123
x = -94.71/(-1.123)
x = 84.3365984
x = 84.3365984
| x^2+15=51 | | 4780+4780*.05=x | | 9x-6x+7=x-4+11 | | y=5*3-3 | | 0.03m+0.21=0.1-0.02m+0.03 | | (7x-2)(3x+4)=0 | | 4x+36=x | | -7y+6=-8y+1 | | n^3+8n^2=0 | | -2(3a+2b)+3(2a+3b)= | | 4x-1+31=90 | | x/11=16 | | x+10x+9=0 | | 100x+300=-200 | | 3k-2h+7+k-2= | | (x+1)(x+1)=2.25 | | 392=770/770-x*349 | | x/3+3=-2 | | 2x^2+x+1=2 | | x-104=5 | | 4x^2-11x-72=0 | | 8(2z+4)-3(3z-6)= | | 4-(9x-5)=45 | | (6x^2-3x^3)-(4x^2-5x^3)=y | | 10(x-4)=-35x | | m-19=-45 | | 4/5x-1/4+14=9/10x | | 2x+7f-9x+21g+5x= | | (1)/(4x^2-25)+(6)/(2x+5) | | (6x^2-3x^3)-(4x^2-5x^3)=0 | | -7/6+5 | | 6(2x-4)=2(6x+8) |