You want to put this in the form (x+b)^2 + c
To do this take half of the coefficient of b from the ordinal form which is 6/2=3 as use this as your new b
This give you (x+3)^2.
If you foil this out you get x^2 +6x +9 so you have added 9 to the original expression so now all you need to do is subtract 9 to keep things balanced
The final expression then is (x+3)^2 -9
<u> So c= -9</u>
The three angles of a triangle add up to 180.
Since you know that two angles add up to 80, you know that the third angle is 100.
3/45 because it is simplified 15/5=3 and 225/5=45