F(x) = 4.25x + 50
for 6 hrs....x = 6
f(6) = 4.25(6) + 50
f(6) = 25.50 + 50
f(6) = 75.50 <==
Correct Option:Option B
Solution:The given expression is:

cos(3x) can be written as cos(2x +x). Expanding it, we get:

Using this value of cos(3x) in given equation, we get:
Jill will pick up 24 and jack will pick up 25
For no real solution, you must have b^2 - 4ac of the quadratic formula be less than 0.
a = 1; b = 2; c = C
b^2 - 4ac < 0
2^2 - 4(1)(C) < 0
4 - 4C < 0
-4C < -4
C > 1
The only choice greater than 1 is 3.
Answer: the 4th choice, 3