note that the subtraction changes the sign of each term in the second trinomial ...
combine like terms ...
2012-04-08144208.jpg picture by King_Bradley - Photobucket
You try 4
First thing I do is distribute the - to the second paranthesis so I get 3h^2-h+4
Then I do
-7h^2-8h+1
PLUS
3h^2-h+4
To get
-4h^2-9h+5
Wrong answer, I try subtracting
-7h^2-8h+1
minus
3h^2-h+4
______________
-10h^2-7h+5
What am I doing wrong?