Final answer:
To show that the function is continuous on the given interval [4, infinity), we need to demonstrate existence, uniqueness, and limit. The function f(x) = x + x - 4 satisfies all three conditions.
Step-by-step explanation:
To show that a function is continuous, we need to show that it satisfies three conditions: existence, uniqueness, and limit. Let's consider the function f(x) = x + x - 4 on the interval [4, infinity).
Existence: The function is defined for all values of x in the interval [4, infinity).
Uniqueness: The function is a polynomial, so it is continuous everywhere.
Limit: We need to show that the limit as x approaches any value in the interval [4, infinity) exists and equals the function value at that point. Taking the limit as x approaches a value in the interval, we get:
lim(x->a) (x + x - 4) = a + a - 4 = 2a - 4
This limit exists and equals 2a - 4 for any value of a in the interval [4, infinity). Therefore, the function is continuous on the given interval [4, infinity).