Question 118229
If {{{1/x + 1/a = 1/b}}} then what is {{{x}}}

{{{1/x + 1/a = 1/b}}}..........multiply both sides by {{{xab}}}


{{{(1/x)(xab) + (1/a)(xab) = (1/b)(xab)}}} 


{{{(1/cross(x))(cross(x)ab) + (1/cross(a))(x(cross(a))b) = (1/cross(b))(xa(cross(b)))}}} 


{{{ab + xb = xa}}}......move {{{ab}}} to the rght and {{{xa}}}to the left

 {{{xb- (xa) = -(ab)}}}......

 {{{x(b- a) = -(ab)}}}......

{{{x = -(ab)/(b- a)}}}......