cos (2x) = cos x
2 cos^2 x -1 = cos x using the double angle formula
2 cos ^2 x -cos x -1 =0
factor
(2 cos x+1) ( cos x -1) = 0
using the zero product property
2 cos x+1 =0 cos x -1 =0
2 cos x = -1 cos x =1
cos x = -1/2 cos x=1
taking the arccos of each side
arccos cos x = arccos (-1/2) arccos cos x = arccos 1
x = 120 degrees x=-120 degrees x=0
remember you get 2 values ( 2nd and 3rd quadrant)
these are the principal values
now we need to add 360
x = 120+ 360n x=-120+ 360n x = 0 + 360n where n is an integer
Direct variation is y=kx where k is a constant
the fiest way to see if it is direct or not, is if x increases, then y increases as well,
then we see if y=kx is valid, basically if we have a constant of variation
the first one x increase and y increase
see if same constant
y=kx
-4.5=-3k
1.5=k
so
see next one
-1 and 3
-3=-1(k)
-3=-1(1.5)
-3=-1.5
false
not it
2nd is increase and y decrease, so not direct variation
3rd is x is same but y increase so nope
4th is x increase and y increase, now test the constant
-7.5=-3k
2.5=k
-1 and -2.5
-2.5=-1k
-2.5=-1(2.5)
-2.5=-2.5
true
answer is last option
Answer:
a) 1/64
b) 1/4096
Step-by-step explanation:
As you can tell from the example, the exponent of 1/2 is the number of heads in a row.
a) p(6 heads in a row) = (1/2)^6 = 1/(2^6) = 1/64
b) p(12 heads in a row) = (1/2)^12 = 1/(2^12) = 1/4096
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<em>Additional comment</em>
The probability of a head is 1/2 because we generally are concerned with a "fair coin." That is defined as a coin in which each of the 2 possible outcomes has the same probability, 1/2. Similarly, a "fair number cube" has 6 faces, and the probability of each is defined to be the same as any other, 1/6. Loaded dice and unfair coins do sometimes show up in probability problems.
