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
So 1 and 1/2 divided by 1/8. That’s the same as 3/2 divided by 1/8.
Keep change flip.
3/2 x 8/1
24/2= 12
ᴀɴsᴡᴇʀ:
<u>1.Example, x²-25 can be factored as (x+5)(x-5).</u>
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<u>2.This method is based on the pattern (a+b)(a-b)=a²-b², which can be verified by expanding the parentheses in (a+b)(a-b).</u>
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<u>3.When an expression can be viewed as the difference of two perfect squares, i.e. a²-b², then we can factor it as (a+b)(a-b). For example, x²-25 can be factored as (x+5)(x-5).</u>
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#4 is 47, 48, 49
47+48+49=144
Answer:
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Step-by-step explanation:
