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:
{x,y} = {6/5,23/10}
Step-by-step explanation:
[1] 7x + 2y = 13
[2] 4x + 4y = 14 <---------- linear equations given
Graphic Representation of the Equations : PICTURE
2y + 7x = 13 4y + 4x = 14
Solve by Substitution :
// Solve equation [2] for the variable y
[2] 4y = -4x + 14
[2] y = -x + 7/2
// Plug this in for variable y in equation [1]
[1] 7x + 2•(-x +7/2) = 13
[1] 5x = 6
// Solve equation [1] for the variable x
[1] 5x = 6
[1] x = 6/5
// By now we know this much :
x = 6/5
y = -x+7/2
// Use the x value to solve for y
y = -(6/5)+7/2 = 23/10
// Plug this in for variable y in equation [1]
[1] 7x + 2•(-x +7/2) = 13
[1] 5x = 6
// Solve equation [1] for the variable x
[1] 5x = 6
[1] x = 6/5
// By now we know this much :
x = 6/5
y = -x+7/2
// Use the x value to solve for y
y = -(6/5)+7/2 = 23/10
20x1/4=5
Think thats what you mean
1/2 divided by 3 is 1/6.
So your answer is 1/6 pounds each person.
slope intercept form is: y = mx + b
m = slope
b = y-intercept
In the equation y = 1/4x + 8
m = 1/4 = slope
b = 8 = y-intercept