Question 161761
Factor each polynomial. 
{{{h^2-9hs+9s^2 }}}

Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to 9hs
First Number---- Second Number---- Sum
1………………………...........9………………………….........10
3………………………...........3………………………….........6
-1……………………..........-9………………………........…-10
-3……………………..........-3………………………........…-6

None of these factors add to 9hs.
polynomial {{{h^2-9hs+9s^2 }}} cannot be factored


26. 
Factor using AC method 

{{{21x^2+2x-3}}} 

*[invoke change_this_name4450 21, 2, -3, "x"]

72.Factor 
{{{3x^2-18x-48 }}}

*[invoke change_this_name4450 3, -18, -48, "x"]


18. Factor 
{{{2h^2-h-3}}}

*[invoke change_this_name4450 2, -1, -3, "x"]