Respuesta :
Answer:
The correct option is: B. 9
Step-by-step explanation:
The number of tennis balls, [tex]P(n)[/tex] , in [tex]n[/tex] layers of the square pyramid is given by: [tex]P(n)=P(n-1)+n^2[/tex]
As the stack of the tennis balls is in shape of a square pyramid, that means in the top layer, there will be one ball. So, [tex]P(1)= 1[/tex]
Now, if [tex]n=2,[/tex] then [tex]P(2)= P(2-1)+(2)^2 = P(1)+4=1+4=5[/tex]
If [tex]n=3,[/tex] then [tex]P(3)=P(3-1)+(3)^2=P(2)+9=5+9=14[/tex]
If [tex]n=4,[/tex] then [tex]P(4)=P(4-1)+(4)^2 = P(3)+16=14+16=30[/tex]
That means, the number of tennis balls from the top layer will be: 1, 5, 14, 30, .......
So, the number of tennis balls that Coach Kunal could not have is 9.
