Answer: I need help pls
Step-by-step explanation:
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
Answer:
c
Step-by-step explanation:
Answer:

Step-by-step explanation:
When adding rational numbers, if the denominator is the same you simply keep the denominator (bottom of fraction) as it is and apply the operation given to the numerator ( top of fraction )
So we have 
==> remove parenthesis and apply signs

==> simplify numerator by combining like terms

and we are done!
Note:
like terms are terms with the same variable and exponent
An example of like terms are 6x^7 and 3x^7 as they have x as a variable and a power of 7
The like terms being combined here were (6x² and 4x²) and (5 and -2)
The Answer would be x=72. Why? Because

is your %. You Cross multiply 240 * 30 = 100x
240 time 30 = 7200. you want x to be alone so you do 7200 divided by 100 equaling 72. So you get x=72.