Answer:
volume = length x width x height
v=11x5x11 = 605
hope that answers your question
A)
The discriminant (radicand) is √(b^2-4ac), let us call this "d" for the discriminant.
If:
d<0, there are no real solutions (though there are two imaginary ones)
d=0, there is one real solution
d>0, there are two real solutions.
In this case, d=12^2-4(4)9
d=144-144
d=0
So there is one real solution.
B)
9x^2-30x+25=0
9x^2-15x-15x+25=0
3x(3x-5)-5(3x-5)=0
(3x-5)(3x-5)=0
(3x-5)^2=0
x=5/3
x=1 2/3
This is a problem of Permutations. We have 3 cases depending on the number of B's. Since no more than three B's can be used we can use either one, two or three B's at a time.
Case 1: Five A's and One B
Total number of letters = 6
Total number of words possible = 
Case 2: Five A's and Two B's
Total number of letters = 7
Total number of words possible = 
Case 3: Five A's and Three B's
Total number of letters = 8
Total number of words possible = 
Total number of possible words will be the sum of all three cases.
Therefore, the total number of words that can be written using exactly five A's and no more than three B's (and no other letters) are 6 + 21 + 56 = 83