Does anyone know how to do this

a. If , then , so

b. When , we're told has a horizontal tangent, which has slope . So we have

where is any integer, whose smallest positive value occurs for , giving .

c. The equation is separable:

Integrate both sides to get

when , so we find

Then the particular solution to the DE is

step-by-step explanation:

the shape,the size and the distance