Answer:
(8, 5) (Answer C)
Step-by-step explanation:
Write this system of linear equations in a (vertical) column:
4x - 3y = 17
5x + 4y = 60
Let's eliminate y through addition/subtraction:
Multiply 4x - 3y = 17 by 4, obtaining 16x - 12y = 68, and
multiply 5x + 4y = 60 by 3, obtaining 15x + 12y = 180. Then we have:
16x - 12y = 68
15x + 12y = 180
----------------------
31x = 248, and so x = 248/31 = 8.
Now find y. Substitute 8 for x in 5x + 4y = 60: 5(8) + 4y = 60, or
4y = 60 - 40 = 20.
Thus, y = 20/4, or y = 5.
The solution is (8, 5) (Answer C)
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:
72.3%
Step-by-step explanation:
-2.54
Step-by-step explanation:
rockstar