pleeeeeeease someone help explain this to me..... (q^(-2)-r^(-2))/q^(-1)-r^(-1))

Question

a_clan · Answer

(q^(-2)-r^(-2))                     1            1                  r² - q²
-------------  =              ---   -   ---                  -------   .......(Take LCM)
(q^(-1)-r^(-1))                     q²          r²                     q²r²
                                   -----------------   = ---------------
                                            1          1                      r - q
                                          ---  -   ---                  --------  .......(take LCM)
                                            q           r                       qr


= r² - q²           qr               q+r
  ------- * --------  =  --------       ....(answer)
   q²r²             r - q               qr