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
answers are in the pictures
If you are looking for how to turn that worded problem into an equation...
Heres the answer you're looking for
3x-11
9514 1404 393
Answer:
y = 38x
Step-by-step explanation:
The constant of proportionality (k) is the value of y when x=1. The table shows that to be 38. Then the equation is ...
y = kx
y = 38x
Answer:
I believe (D)
Step-by-step explanation:
-5x + 7 = -13
-7 -7
-5x = -20
-5/-5 -20÷-5
x=4
