Question 1100167
start with S = D^2/ (D-R)^2


multiply both sides of the equation by (D-R)^2 and divide both sides of the equation by S.


you will get (D-R)^2 = D^2 / S


take the square root of both sides of the equation.


you will get D-R = plus or minus sqrt(D^2 / S)


subtract D from from both sides of the equation.


you will get -R = -D plus or minus sqrt(D^2 / S)


multiply both sides of the equation by -1.


you will get R = D - (plus or minus sqrt(D^2 / S)


this results in R = D minus or plus sqrt(D^2 / S).


this is the same as R = D plus or minus sqrt(D^2 / S).


that's your solution.


to determine if this solution is accurate, then work your way back and solve for S.


you will start with either R = D plus sqrt(D^2 / S) or R = D minus sqrt(D^2 / S).


in both cases, you will be able to get back to the original equation.