Answer:
D. 9
Step-by-step explanation:
We are told in the question that: The number of tennis balls represented by P(n), in n layers of the square pyramid is given as
P(n) = P(n - 1) + n²
Let's take the first layer
n = 1
P(1) = P(1 - 1) + 1²
P(1) = 1 tennis ball.
It is important to note that the first layers we have one tennis ball.
Let's take the second layer
n = 2
P(2) = P(2 - 1) + 2²
P(2) = P(1) + 2²
Note that: P(1) above = 1
P(2) = 1 + 2²
P(2) = 5 tennis balls
It is important to note that the second layer we have five tennis balls
Let's take the third layer
n = 3
P(3) = P(3 - 1) + 3²
P(3) = P(3 - 1) + 3²
P(3) = P(2) + 3²
Note that: P(2) above = 5
P(3) = 5 + 3²
P(3) = 14 tennis balls
It is important to note that the second layer we have fourteen tennis balls
Let's take the fourth layer
n = 4
P(4) = P(4 - 1) + 4²
P(3) = P(4 - 1) + 4²
P(3) = P(3) + 4²
Note that: P(3) above = 14
P(3) = 14 + 4²
P(3) = 30 tennis balls
It is important to note that the fourth layer we have thirty tennis balls
Hence, the number of tennis balls from the first four layers will be: 1, 5, 14, 30,
So, the number of tennis balls that Coach Kunal could not have is 9.
