Answer:
6,7
Step-by-step explanation:
X = 18°
cos 54° = sin 36°
cos 3 x = sin 2 x
cos ( 2 x + x ) = sin 2 x
cos 2 x cos x - sin 2 x sin x = 2 sin x cos x
( cos² x - sin² x ) cos x - 2 sin² x cos x = 2 sin x cos x / : cos x
( divide both sides by cos x )
cos² x - sin² x - 2 sin² x = 2 sin x
1 - sin² x - 3 sin² x - 2 sin x = 0
- 4 sin² x - 2 sin x + 1 = 0 substitution: u = sin x
- 4 u² - 2 u + 1 = 0
u = 2 -√20 / - 4
sin 18° = (√ 5 - 1 )/4 
cos 18° = √( 1² - ((√5 - 1)/4)²
cos 18° = (10+2√5)^(1/2) / 4
Divide 40 by 8 minutes to find the quantity per minute for one machine:
40 / 8 = 5 per minute.
One machine does 5 envelopes per minute.
Now divide 120 by 5 to find the number of machines needed:
120 / 5 = 24
24 machines would be needed.
Answer:

Step-by-step explanation:
<h3>(2,1) (4,2)</h3>

1. the graph of 2x + 1 = y for all real numbers will be a line. the graph with the restricted domain will be a line segment meaning it has endpoints (1, 3) and (4, 9).
2. is open ended, meaning you can make A, B, C anything you want as long as what they specify is met.
(a) A = 0
(0)x + By = C
let's make B = 1 and C = 5
y = 5
(b) B = 0
Ax + (0)y = C
let's make A = 1 and C = 5
x = 5
(c) C = 0
Ax + By = 0
let's make both A and B = 1
x + y = 0
3. plot both intercepts (x on x-axis, y on y-axis) then draw a line through the dots.
4-7. linear equations do not have exponents on any of the variables. 1/y is the same as y^(-1) so both 4 and 7 are non-linear.
8-13. you will have to graph these. put them in slope intercept form: y = mx+b if they're not already , plot the y-intercept first (0, b) then use the slope m draw the line by going rise over run.
example 13.
3x + 4y = 12
4y = -3x + 12
y = (-3/4) + 3
plot (0,3)
go down -3 , right 4 make a point.
reverse from (0,3) go up 3 left -4 and make a point. connect with line.