Step-by-step explanation:
(f + g)(x) = f(x) + g(x) = (4x² + 1) + (x² - 5) = 5x² - 4. (D)
Answer:
Differential equation

Solution

Value of constant k=0.327 days^(-1)
The rumor reaches 80% at 8.48 days.
Step-by-step explanation:
We know
y(t): proportion of people that heard the rumor
y'(t)=ky(1-y), rate of spread of the rumor
Differential equation

Solving the differential equation

Initial conditions:

Value of constant k=0.327 days^(-1)
At what time the rumor reaches 80%?

The rumor reaches 80% at 8.48 days.
A = {1, 2, 5, 6, 8}
{1} U {2, 5, 6, 8}
{2} U {1, 5, 6, 8}
{5} U {1, 2, 6, 8}
{6} U {1, 2, 5, 8}
{8} U {1, 2, 5, 6}
{1, 2} U {5, 6, 8}
{1, 5} U {2, 6, 8}
{1, 6} U {2, 5, 8}
{1, 8} U {2, 5, 6}
{1, 2, 5} U {6, 8}
{1, 2, 6} U {5, 8}
{1, 2, 8} U {5, 6}
{1, 5, 6} U {2, 8}
{1, 5, 8} U {2, 6}
{1, 6, 8} U {2, 5}
The answer is 15 distinct pairs of disjoint non-empty subsets.
The first one because it goes through pretty much all the points on the graph.