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:
29 and 35
Step-by-step explanation:
x+y=64
x-y=6
Solve by substitution.
x=6+y
6+y+y=64
6+2y=64
y=29
Then plug in 29 for y.
x+29=64 ......35
Answer: x=-1
Step-by-step explanation:
Answer:
$75
Step-by-step explanation:
Joni currently earns $300 per week (given)
To find how much more she will earn each week, write an expression adding the original pay and the raise amount.
$300 + 25%
Find 25 as a decimal for multiplication
25% = 25/100 = 0.25
Write an expression to represent the scenario
Expression example 1:
$300 + 0.25(300)
This expression adds the original pay and the new raise together.
Expression example 2:
$300 (1.25)
This expression already takes the new pay into account by finding 125% of the original pay.
Simplify both expressions
Expression 1:
$300 + 0.25(300)
$300 + $75
$375
Expression 2:
$300 (1.25)
$375
Both expressions represent the same scenario and therefore come out to the same result. Now that we know how much Joni made after the raise, we need to find how much more money she will earn in a week with the following equation.
New amount - original amount = amount increase
Substitute known values into the equation
$375 - $300
Simplify
$75
Joni will earn $75 more each week.
Let me know if you have any questions!