Find the exact value of the expression.cos 40° cos 20° - sin 40° sin 20°
A. 
B. 
C. 
D. 
Answer: D
Mathematics
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State the domain and range of the function.f(x) = 
A. Domain = (-?, ?); range = (7, ?) B. Domain = (-?, ?); range = (0, 7) C. Domain = (-?, ?); range = (-?, ?) D. Domain = (0, ?); range = (-?, ?)
Mathematics
Solve for x. Check your answer. If there is no solution, say so.
= 
A. x = 416
B. x = 
C. x = 26
D. x = 
Mathematics
Use the imaginary unit to write the expression.
A. 2i
B. -i
C. ±2
D. -2i
Mathematics
Find the second derivative of 
A. 
x 1/2 - 
x -3/4 + 5
B. 
x -1/2 - 
x -7/4
C. 
x -1/2 + 
x -7/4
D. 
x 1/2 - 
x -3/4 + 5
E. x 1/2 + 
x -7/4
Mathematics