Since area is length times width, it would be the factors of the equation for the area.
X2+11x+28 factors into...
Length is x+7 so...
Width is x+4
R-7=7 add the seven from both sides, leaving the r alone, because this is what you are trying to find. Thus the answer is r=14.
Set up your parentheses, and put x in the front of both because x is squared. It should look like this: (x )(x ). Next, you find notice that one sign must be positive, and one must be negative. Then, you find the factors of 36. 6 and 6, 3 and 12, 1 and 36, 18 and 2, and 9 and 4. You then guess and check with the different signs and factors what will get you back to the trinomial using the FOIL method. When you do this, you should get (x-9)(x+4).
Your answer is C for sure I am!
