Question 238557
Add simplify if possible
;
{{{(6z)/(z^2-36)}}} + {{{z/(z-6)}}} 
The 1st denominator is the "difference of squares" and can be factored to
{{{(6z)/((z+6)(x-6))}}} + {{{z/(z-6)}}}
(z-6)(z+6) would be the common denominator so we have:
{{{(6z + z(z+6))/((z+6)(x-6))}}} = {{{(6z + z^2 + 6z)/((z+6)(x-6))}}} = {{{(z^2 + 12z)/((z+6)(x-6))}}} = {{{z(z + 12)/((z+6)(x-6))}}}
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Factor completely
25s^2 - 121
Both 25 and 121 are perfect squares, you should recognize this as the "difference of squares"
(5s - 11) (5s + 11)
:
Check this by FOILing
25s^2 + 55s - 55s - 121
Middle terms cancel
25s^2 - 121