Find the 9th term of the geometric sequence 9, -27, 81, ...

Answer:

Either [tex]x = (-\pi / 6)[/tex] or [tex]x = (\pi / 6)[/tex].

Step-by-step explanation:

Angle sum identity for cosine:

[tex]\cos(a + b) = \cos(a)\, \cos(b) - \sin(a) \, \sin(b)[/tex].

Double-angle identity for cosine and sine:

[tex]\begin{aligned}& \cos(2\, a)\\ &= \cos^{2}(a) - \sin^{2} (a) \\ &= (\cos^{2}(a) + \sin^{2}(a) - 2\, \sin^{2}(a) \\ &= 1 - 2\, \sin^{2}(a)\end{aligned}[/tex].

[tex]\sin(2\, a) = 2\, \cos(a) \, \sin(a)[/tex].

The secant of an angle is the inverse reciprocal of the cosine of that angle:

[tex]\displaystyle \text{$\sec(x) = \frac{1}{\cos(x)}$ if $\cos(x) \ne 0$}[/tex].

Apply these identities to rewrite the left-hand side of the equation.

[tex]\begin{aligned} & \sec(x) \, \cos(3\, x) \\ =\; & \frac{1}{\cos(x)} \cdot \cos(3\, x) \\ =\; & \frac{1}{\cos(x)} \cdot (\cos(x)\, \cos(2\, x) - \sin(x)\, \sin(2\, x)) \\ =\; &\cos(2\, x) \\ & - \frac{1}{\cos(x)} \cdot (\sin(x)\, \sin(2\, x)) \\ =\; & \cos(2\, x)\\ & - \frac{1}{\cos(x)} \cdot (\sin(x) \cdot (2\, \sin(x)\, \cos(x))) \\ =\; & \cos(2\, x) - 2\, \sin^{2}(x) \\ =\; & (1 - 2\, \sin^{2}(x)) - 2\, \sin^{2}(x) \\ =\; &1 - 4\, \sin^{2}(x) \end{aligned}[/tex].

Solve the rewritten equation:

[tex]\displaystyle \sin^{2}(x) = \frac{1}{4}[/tex].

Either [tex]\sin(x) = (1/2)[/tex] or [tex]\sin(x) = (-1/2)[/tex].

The question required that [tex](-\pi / 2) \le x \le (\pi / 2)[/tex]. The sine function is one-to-one over this range. In other words, for each [tex]y[/tex] between [tex](-1)[/tex] and [tex]1[/tex], there is exactly one [tex]x[/tex] between [tex](-\pi / 2)[/tex] and [tex](\pi / 2)[/tex] such that [tex]\sin(x) = y[/tex].

If [tex]\sin(x) = (-1/2)[/tex] and [tex](-\pi / 2) \le x \le (\pi / 2)[/tex], then [tex]x = (-\pi / 6)[/tex].

Otherwise, if [tex]\sin(x) = (1/2)[/tex] and [tex](-\pi / 2) \le x \le (\pi / 2)[/tex], then [tex]x = (\pi / 6)[/tex],

Verify that [tex]\cos(x) \ne 0[/tex] for either of the two [tex]x[/tex] values, such that the [tex]\sec(x)[/tex] in the original equation takes a real value.

Answer: C. 85°

Step-by-step explanation:

Answer:

I look lik dis almost dreads and then them types of braces and my eye brows look like that and I got a tattoo on my face but my eyes are blue and I have contacts so no more glasses

Answer:

I believe it is C but it's good to double check

Step-by-step explanation:

Answer:

Step-by-step explanation:

b

The probability distribution for all possible values of X are given in the discrete probability table ;

Fair coin = {H, T}

card = {J, Q, K, A}

Sample space :

Probability of winning ; P(Winning) = 2/8 = 1/4 = 0.25

Probability of not winning ;

1 - P(wininng) = 1 - 1/4 = 3/4 = 0.75

X : ____ winning ____ not winning

P(X) : ____ 0.25 ________ 0.75

Learn more : https://brainly.com/question/25274933

Answer:

D

Step-by-step explanation:

Hope this is correct and helps

Answer:

D

Step-by-step explanation:

I'm not completely sure but A is constant cuz it don't move B is increasing C is same as A and D Is decreased

Answer:

Step-by-step explanation:

Gogli complexes packages proteins, while endoplasmic reticulums transport proteins made by the gogli complexes around the cell.

[tex]\large\underline{\sf{Solution-}}[/tex]

We have to evaluate the given expression.

[tex] \rm = \sqrt{ \dfrac{1 - \sin(x) }{1 + \sin(x) } } [/tex]

If we multiple both numerator and denominator by 1 - sin(x), then the value remains same. Let's do that.

[tex] \rm = \sqrt{ \dfrac{[1 - \sin(x)][1 - \sin(x) ]}{[1 + \sin(x)][1 - \sin(x) ]} } [/tex]

[tex] \rm = \sqrt{ \dfrac{[1 - \sin(x)]^{2}}{1- \sin^{2} (x) } } [/tex]

We know that:

[tex] \rm \longmapsto { \sin}^{2}(x) + \cos^{2}(x) = 1[/tex]

[tex] \rm \longmapsto \cos^{2}(x) = 1 - { \sin}^{2}(x)[/tex]

Therefore, the expression becomes:

[tex] \rm = \sqrt{ \dfrac{[1 - \sin(x)]^{2}}{\cos^{2} (x)}} [/tex]

[tex] \rm = \dfrac{1 - \sin(x)}{\cos(x)}[/tex]

[tex] \rm = \dfrac{1}{\cos(x)} - \dfrac{ \sin(x) }{ \cos(x) } [/tex]

[tex] \rm = \sec(x) - \tan(x) [/tex]

[tex] \sqrt{ \frac{ \cos(n) }{1 + \: \sin(n) } } [/tex]

see the attachment!!

hope it helps

#carryolearning

Answer:

1, 11x + 3y + 15z

2, 3x + 12y + -5z

Step-by-step explanation:

all you need to do is combined the like terms and make sure the signs (positive and negative signs) are right

Answer:

A = -3

Step-by-step explanation:

-16-7(-3)=5

Answer:

I can't help you if there's no picture lol

Answer:

18+3

Step-by-step explanation:

3x6= 18

and 18+3=21

The formula ½ bh finds the area of a triangle.

Please check the picture.

Answer:

Triangle

Step-by-step explanation:

b -  base of the triangle

h - height or altitude

Answer:

After turn one she will have 0 points !

Step-by-step explanation:

After turn one she will have 0 points

After turn 2 she will have 8 points

After turn 3 she will have 7 points

She will not earn bonus points because she could not reach ten points

(Hope this helps can I pls have brainlist (crown)☺️)

Answer:

a) = 4.198

b) = 4.146

Step-by-step explanation:

a) 15.444/6+0.232*7

do pemdas

=15.444/6+(0.232*7)

=(15.444/6)+1.624

=2.574+1.624

a) = 4.198

b) (1.709+0.364)*6/3

pemdas again

=(2.073) *6 / 3

=12.438 / 3

b) =4.146

Hope this helps :)

Answer:

A 4.198 and b is 2.073

Step-by-step explanation:

i hope this is right

Answer: 20

Step-by-step explanation:

Answer:

We need the options

Step-by-step explanation:

...

Answer:

Answer:18.5

Step-by-step explanation:

10+8=18

18*5=90

90/4

22.5-4=18.5

Have a happy day! <3Miss Hawaii

Answer:

16

Step-by-step explanation:

sum of 8 and 10=18

5 times of sum of 8 and

10= 18×5=80

1/4 of 5 times of sum of 8 and

10= 1/4×80=20

and then subtracted 4 from

20 =20-4=16

Answer:

k=4+h

...................

Answer:

7.5m

:) hoped this helped!

Step-by-step explanation:

Answer:

y = x-7

Step-by-step explanation:

Slope intercept form is

y = mx+b  where m is the slope and b is the y intercept

2y -2x = -14

Add 2x to each side

2y-2x+2x= 2x-14

2y = 2x-14

Divide by 2

2y/2 = 2x/2 -14/2

y = x-7

Answer:

a) 68

b)60

Step-by-step explanation:

a) 85% = 0.85

0.85 * 80 = 68

b) let x be the unknown number.

35% = 0.35

0.35x = 21

x = 60

Answer:

Step-by-step explanation:

a, 85% of 80

85% of 80

= 85/100*80

=85/100*80

=0.85*80

=68.

b, 21 is 35%

21 is 35%

=21*35/100

=21*0.35

=7.35.

hope this helps you dear and have a nice day

Answer:

Step-by-step explanation:

65% of 51 = [tex]\dfrac{65}{100}*51[/tex]

                = 0.65 *51

                = 33.15

Answer:

x = 5

Step-by-step explanation:

[tex]6x - 20 = 2x \\ - 20 = 2x - 6x \\ - 20 = - 4x \\ \frac{ - 20}{ - 4} = x = 5[/tex]

I must speak in your language

ddddwfdwfd qdqfqfqqdqdqdqddqdqdq

Answer:

1.6 (decimal), 1 6/10 (proper), and 8/5 (improper)

Step-by-step explanation:

If it’s 2/5 in 1/4 and to get one while you need four 1/4 you need to multiply to get how much it can fill in that 4/4. To do this multiply 2/5 by 4 which is 1.6 (decimal) and 1 6/10 fractional. Or if you want it improper, 8/5

Answer:

5

Step-by-step explanation:

7 x 5 =  35

35 + 3 = 38

Answer:

AAS

Step-by-step explanation:

I'm pretty sure its this, but im sorry if im wrong!