Final answer:
The function f(x)=x^2+11 is always increasing, therefore it increases on the interval (-∞, ∞). Continuous probability functions define probability as the area under the curve, with the total area equalling 1 for the entire function.
Step-by-step explanation:
The student is seeking help in finding the interval on which the function f(x)=x^2+11 is increasing. To determine this, we calculate the first derivative f'(x), which is simply 2x. Since this derivative is positive for all values of x greater than 0, the function is always increasing for x > 0. However, as the derivative is 0 at x = 0 and positive again for x < 0, we can conclude that the function is actually increasing for all values of x. Therefore, the function is increasing on the interval (-∞, ∞), which represents the entire real line.
When we talk about continuous probability functions, the area under the curve represents the probability. For non-negative functions that represent probability distributions, the total area under the curve must equal 1 since the probability cannot exceed 100%. In such cases, the probability is defined as the area under the curve between two points on the x-axis. Considering continuous probability functions, intervals outside the defined range, like P(x > 15) when the function is defined between 0 ≤ x ≤ 15, will have a probability of 0.