Answer:
37.5 Gallons will be used after a 15-minute shower.
50 Gallons will be used after a 20-minute shower.
DM me if you need an explanation.
37. 6r^2
41. B
42. B
44. C
Note that √(4 - t²) is defined only as long as 4 - t² ≥ 0, or -2 ≤ t ≤ 2. Then the real integral exists only if -2 ≤ x ≤ 2. (Otherwise we deal with complex numbers.)
If x = 2, then the integral corresponds to the area of a quarter-circle with radius 2. This means that the integral has a maximum value of 1/4 • π • 2² = π.
On the opposite end, if x = -2, then the integral has the same value, but the integral from 0 to -2 is equal to the negative integral from -2 to 0. So the minimum value is -π.
For all x in between, we observe that the integrand is continuous over the rest of its domain, so F(x) is continuous.
Then the range of F(x) is the interval [-π, π].
The best way for him to check his answer would be to simply plug in the value found for x into the equation.
4(2) - 6 = 2
8 - 6 = 2
2 = 2
