z^2-81/7z+28 * z+4/z-9
multiply & simplify someone
plz help i cant figure out this answer

Question

z^2-81/7z+28 * z+4/z-9 
multiply & simplify someone
 plz help i cant figure out this answer

anonymous · Answer

z^2-81/7z+28 * z+4/z-9 
z^2-81              z+4
-------   *     ----------
7z+28

anonymous · Answer

z^2-81              z+4
-------   *     ----------
7z+28               z-9

anonymous · Answer

z^2-9^2              z+4
-------   *     ----------
7(z+4)               z-9

anonymous · Answer

(z-9)(z+9)              z+4
-------   *     ----------
7(z+4)               z-9

anonymous · Answer

cancel Z-9 

(z+9)              z+4
-------   *     ----------
7(z+4)                    1

anonymous · Answer

cancel z+4
(z+9)                    1
-------   *     ----------
    7                    1

anonymous · Answer

(z+9)                 
-------
    7