Use Stokes' theorem for both parts, which equates the surface integral of the curl to the line integral along the surface's boundary.
a. The boundary of the hemisphere is the circle
in the plane
, where the curl is
. Green's theorem applies here, so that

which means the value of the line integral is 3 times the area of the circle, or
.
b. The closed sphere has no boundary, so by Stokes' theorem the integral is 0.
Answer:
y = 5 e^r * t
Let y be the population in billions and t the value of elapsed years
7 = 5 e^r * t is the equation being used where t = 15
7/5 = e^r * t
ln 7/5 = r * t taking ln of both sides
r = .336 / 15 = .0224
y = 5 e^(.0224 t) is then our equation
Check - suppose you want y at 2020
y = 5 e^(.0224 * 20) would be the equation
y = 5 e^.449 = 7.83 billion - seems to be a reasonable answer
Answer: 72 miles
Step-by-step explanation:
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