[tex]▪▪▪▪▪▪▪▪▪▪▪▪▪  {\huge\mathfrak{Question ~}}▪▪▪▪▪▪▪▪▪▪▪▪▪▪[/tex]

Prove that ~

[tex] \dfrac{d}{dx}\sec(x) = \sec(x) \tan(x) [/tex]


by using first principle of differentiation ~​

Answers

Answer 1

Answer:

METHOD I:

(by using the first principle of differentiation)

We have the "Limit definition of Derivatives":

[tex]\boxed{\mathsf{f'(x)= \lim_{h \to 0} \{\frac{f(x+h)-f(x)}{h} \} ....(i)}}[/tex]

Here, f(x) = sec x, f(x+h) = sec (x+h)

Substituting these in eqn. (i)

[tex]\implies \mathsf{f'(x)= \lim_{h \to 0} \{\frac{sec(x+h)-sec(x)}{h} \} }[/tex]

sec x can be written as 1/ cos(x)

[tex]\implies \mathsf{f'(x)= \lim_{h \to 0} \frac{1}{h} \{\frac{1}{cos(x+h)} -\frac{1}{cos(x)} \} }[/tex]

Taking LCM

[tex]\implies \mathsf{f'(x)= \lim_{h \to 0} \frac{1}{h} \{\frac{cos(x)-cos(x+h)}{cos(x)cos(x+h)} \} }[/tex]

By Cosines sum to product formula, i.e.,

[tex]\boxed{\mathsf{cos\:A-cos\:B=-2sin(\frac{A+B}{2} )sin(\frac{A-B}{2} )}}[/tex]

=> cos(x) - cos(x+h) = -2sin{(x+x+h)/2}sin{(x-x-h)/2}

[tex]\implies \mathsf{f'(x)= \lim_{h \to 0} \frac{2sin(x+\frac{h}{2} )}{cos(x+h)cos(x)}\:.\: \lim_{h \to 0} \frac{sin(\frac{h}{2} )}{h} }[/tex]

I shifted a 2 from the first limit to the second limit, since the limits ar ein multiplication this transmission doesn't affect the result

[tex]\implies \mathsf{f'(x)= \lim_{h \to 0} \frac{sin(x+\frac{h}{2} )}{cos(x+h)cos(x)}\:.\: \lim_{h \to 0} \frac{2sin(\frac{h}{2} )}{h} }[/tex]

2/ h can also be written as 1/(h/ 2)

[tex]\implies \mathsf{f'(x)= \lim_{h \to 0} \frac{sin(x+\frac{h}{2} )}{cos(x+h)cos(x)}\:.\: \lim_{h \to 0} \frac{1\times sin(\frac{h}{2} )}{\frac{h}{2} } }[/tex]

We have limₓ→₀ (sin x) / x = 1.

[tex]\implies \mathsf{f'(x)= \lim_{h \to 0} \frac{sin(x+\frac{h}{2} )}{cos(x+h)cos(x)}\:.\: 1 }[/tex]

h→0 means h/ 2→0

Substituting 0 for h and h/ 2

[tex]\implies \mathsf{f'(x)= \lim_{h \to 0} \frac{sin(x+0)}{cos(x+0)cos(x)} }[/tex]

[tex]\implies \mathsf{f'(x)= \lim_{h \to 0} \frac{sin(x)}{cos(x)cos(x)} }[/tex]

[tex]\implies \mathsf{f'(x)= \lim_{h \to 0} \frac{sin(x)}{cos(x)}\times \frac{1}{cos x} }[/tex]

sin x/ cos x is tan x whereas 1/ cos (x) is sec (x)

[tex]\implies \mathsf{f'(x)= tan(x)\times sec(x) }[/tex]

Hence, we got

[tex]\underline{\mathsf{\overline{\frac{d}{dx} (sec(x))=sec(x)tan(x)}}}[/tex]

-  - - - -  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

METHOD II:

(by using other standard derivatives)

[tex] \boxed{ \mathsf{ \frac{d}{dx} ( \sec \: x) = \sec x \tan x }}[/tex]

sec x can also  be written as (cos x)⁻¹

We have a standard derivative for variables in x raised to an exponent:

[tex] \boxed{ \mathsf{ \frac{d}{dx}(x)^{n} = n(x)^{n - 1} }}[/tex]

Therefore,

[tex] \mathsf{ \frac{d}{dx}( \cos x)^{ - 1} = - 1( \cos \: x) ^{( - 1 - 1} } \\ \implies \mathsf{\ - 1( \cos \: x) ^{- 2 }}[/tex]

Any base with negative exponent is equal to its reciprocal with same positive exponent

[tex] \implies \: \mathsf{ - \frac{1}{ (\cos x) {}^{2} } }[/tex]

The process of differentiating doesn't just end here. It follows chain mechanism, I.e.,

while calculating the derivative of a function that itself contains a function, the derivatives of all the inner functions are multiplied to that of the exterior to get to the final result.

The inner function that remains is cos x whose derivative is -sin x.

[tex] \implies \mathsf{ - \frac{1}{ (\cos x )^{2} } \times ( - \sin x) }[/tex]

cos²x can also be written as (cos x).(cos x)

[tex] \implies \mathsf{ \frac{ \sin x }{ \cos x } \times ( \frac{1}{cos x} ) }[/tex]

sin x/ cos x is tan x, while 1/ cos x is sec x

[tex] \implies \mathsf{ \tan x \times \sec x }[/tex]

= sec x. tan x

Hence, Proved!

Related Questions

HELP PLSSS!!!
What is the equation of the line?
A: y=2x+2
B: y= 1/2x -4
C: y=1/2x + 2
D: y=2x-4
GIVING BRAINLY TO CORRECT ANSWER

Answers

Answer:

The answer is C

Step-by-step explanation:

Hope that helps ;)

The answer is D. 99.999%

What is x squared = 100

Answers

❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤

[tex] {x}^{2} = 100[/tex]

❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤

Answer:

your equation is this... x2 - 100

since you have no x term to the first power you can write 0x... like this

x2 + 0x - 100

Now, what numbers will add to 0 and multiply to -100

The numbers 10 and -10 will

10 + -10 = 0

10 * -10 = -100

therefore

(x - 10)(x + 10) is the way you factor it

Step-by-step explanation:

regression and data analysis

Answers

Answer:..

Step-by-step explanation:..

Simplify (12+3i)−(−5+2i)

Answers

Answer:

17+5i

Step-by-step explanation:

add the like terms

double negative equals positive

;)

Answer:

17+i

Step-by-step explanation:

What percent is 30 out of 75?

Answers

Answer:

40%

Step-by-step explanation:

(30/75) x 100 = 40%


bdjdndnd

A necklace is made from 2 purple pyramids and 12 yellow spheres. What is the ratio of pyramids to spheres in its simplest form?​

Answers

Answer:

1:6

Step-by-step explanation:

2:12

\/

1:6

Have a nice day!

     If this is not what you are looking for - comment! I will edit and update my answer accordingly. (ノ^∇^)

- Heather

Answer:

1:6

Step-by-step explanation:

2/12 = 1/6

Which postulate proves these two
triangles are congruent?
A. HL
B. SSA
C. ASA
D. SAS

Answers

b. ssa
it’s not the postulate

HELP ME PLZ

Part A: The sun produces 3.9 ⋅ 1033 ergs of radiant energy per second. How many ergs of radiant energy does the sun produce in 3.25 ⋅ 103 seconds?

Part B: Which is the more reasonable measurement of the distance between the tracks on a railroad:
1.435 ⋅ 10−3 mm or 1.435 ⋅ 103 mm? Justify your answer.

Answers

Answer:

salamat po sa

points.

pa

Step-by-step explanation:

branlest

answer

po

Helppp pleasee ........

Answers

y=3
to solve this you just substitute 4 in for x into the equation and solve for y. since negative 3 plus 7 is 4, y=4

Answer:

y=3

Step-by-step explanation:

y = - x +7

x=4

so y = -4 +7

y = 3

What is 2x-3y=12 on a graph?

Answers

The graph for 2x-3y=12 is

PLEASE HELP WILL GIVE FULL PONITS! 3. Using the known angle, what side is known? What side is unknown? Use opposite, adjacent, or hypotenuse in your answer. (2 points)
Known side: ____________________
Unknown side: ___________________________
4. What trigonometric ratio would you use to find the distance from the base of the tower to your keys? Identify your choice, and then calculate the distance. (4 points: 1 point for the ratio, 2 points for shown work, 1 point for the answer)
Trigonometric ratio (name): ___________________________
Calculation (Show your work):
5. While you're at the top of the tower, you see an ant walking along the edge of the building. If the ant were to walk straight down the side of the tower until it reached the ground, how far would the ant travel? Which trigonometric ratio would you use to find this distance? Use the ratio to find the measurement. (4 points: 1 point for the method, 2 points for shown work, 1 point for the answer)
6. Confirm that your answer to question 5 is correct using the Pythagorean Theorem instead of trig ratios. (3 points)

Answers

Answer:

The trigonometric ratio that I would use to find the distance from the base of the tower to the keys is the tangent; tan (86°) = height / distance.

Step-by-step explanation:

You can draw a right triangle with angle 86°, opposite leg equal to the height (50 meter) and adjacent leg equal to the distance from the base of the tower to the keys: tan (86°) = 50 m / x

=> x = 50 m / tan(86°)

x = 50 m / 14.30 = 0.98 m

if a/3=b/2, what are the following ratios?
a+b/b

Answers

Answer:

1

a+1

es posible q hayan doble respuesta

Step-by-step explanation:

Pasos  

a+b/b

Divide b entre b para obtener 1.

da

d

(a+1)

La derivada de un polinomio es la suma de las derivadas de sus términos. La derivada de cualquier término constante es 0. La derivada de ax  

n

 es nax  

n−1

.

a  

1−1

 

Resta 1 de 1.

a  

0

 

Para cualquier término t excepto 0, t  

0

=1.

1

a+b/b

Divide b entre b para obtener 1.

a+1

Answer ASAP please<3​

Answers

Step-by-step explanation:

So if you multiply both the numerator and denominator by the same number, you get the initial number. Your goal here is to get the same denominator so that you can solve the problem easily! hope it helped!

8/12-3/12=5/12 is correct in order to keep a common denominator :)

A house has increased in value by 3% each year. It was worth £150000 4 years ago. How much is it worth now? Give your answer to a sensible degree of accuracy. morto​

Answers

Answer: 350000

Step-by-step explanation: Hope this helps :) (if wrong please make sure next time add answer that can be picked from it better or if theres no answers maybe give some more detail?)

Select the correct answer.
What is ?

A.

B.

C.

D.

Answers

Answer:

B. 7 1/2

Step-by-step explanation:

1. To solve this problem, we have to multiply 2 1/2 by the reciprocal of 1/3.

In other words, multiply 2 1/2 by the inverse of 1/3, which is 3.

2. (Solving)

[tex]2\frac{1}{2} *3[/tex] [tex]\frac{5}{2} *3[/tex] [tex]\frac{15}{2}[/tex] [tex]7\frac{1}{2}[/tex]

Therefore, the answer is B. 7 1/2.

Answer:

its B mark branli.est pls

Step-by-step explanation:

are 16/72 and 18/81 equivalent rational numbers​

Answers

Answer:

yes

Step-by-step explanation:

[tex]\frac{16}{72}[/tex] ( divide numerator/ denominator by 8, the LCM of 16 and 72 )

= [tex]\frac{2}{9}[/tex]

[tex]\frac{18}{81}[/tex] (divide numerator/ denominator by 9 the LCM of 18 and 81 )

= [tex]\frac{2}{9}[/tex]

Both rational numbers simplify to [tex]\frac{2}{9}[/tex] and are equivalent

Explain why the square root of a number is defined to be equal to that number to the 1/2 power.

Answers

    This is because of the law of indices which says:

[tex]\sqrt[x]{n}[/tex]= [tex]x^{\frac{1}{m} }[/tex]

    So, if we have:

[tex]\sqrt{n}[/tex]

    Then the following will be true because of this math law:

[tex]n^{\frac{1}{2} }[/tex]

Side note: The m value can be greater than n and or less than n, but if it is equal the m and n values cancel out.

Have a nice day!

    I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)

- Heather

What is the diameter of a circular swimming pool with the radius of 8 feet

Answers

Solution: d=2r=2·8=16ft

Diameter when radius is given is just r*2 (radius*2). so the answer is 16

PLZ HELP!!!!
Use the function f(x)=x^2+4x-5 and the coordinate plane. SHOW ALL WORK FOR EACH PART!
What are the values of a, b, and c? (3pts)



Does the parabola open up or down? How do you know? (2pts)



What is the maximum or minimum value? How do you know? (2pts)



What are the x-intercepts? (2pts)



What is the y-intercept? (1pt)


What is the vertex? (2pt)

Answers

9514 1404 393

Answer:

  a) a=1, b=4, c=-5

  b) opens up; a > 0

  c) minimum = -9, the y-value of the vertex

  d) x = -5, 1

  e) y = -5, the value of c

  f) (-2, -9)

Step-by-step explanation:

A graph drawn by a graphing calculator can answer all of these questions quickly and easily.

__

a) The values of 'a', 'b', and 'c' are the values of the coefficients of the terms in the function definition. They refer to the coefficients in the standard form:

  f(x) = ax^2 +bx +c

  f(x) = x^2 +4x -5 . . . . . . . your equation with a=1, b=4, c=-5

__

b) The parabola opens up. This is because the value of 'a' is greater than zero.

__

c) The minimum is the y-value of the vertex. When the function is written in vertex form it is ...

  f(x) = (x -h)^2 +k . . . . . . . . . . . vertex (h, k)

Your function can be put into this form:

  f(x) = x^2 + 4x +4 -5 -4 . . . . . . add and subtract 4 to complete the square

  f(x) = (x +2)^2 -9 . . . . . . . . vertex form. The vertex is (-2, -9).

The y-value of the vertex is -9, the minimum value of the function.

__

d) Solving f(x) = 0, you get ...

  (x +2)^2 -9 = 0

  (x +2)^2 = 9 . . . . . . . . add 9

  x +2 = ±√9 = ±3 . . . . . take the square root; next, subtract 2

  x = -2 ±3 = {-5, 1} . . . . . the x-intercepts

__

e) The y-intercept is f(0) = c = -5.

__

f) The vertex was found in part (c) to be (-2, -9).

PLS HELP NOWWWWWWWWWWWW

Answers

Answer:

is no solution an answer choice cause thats what i got

Step-by-step explanation:

What is the slope of this graph?
A-4
B 1/4
C-1/4
D 4

Answers

Answer:

The answer is D

Step-by-step explanation:

The line has 2 points: (-1;0) and (0;-4)

=> x1 = -1; x2 = 0 => x1 - x2 = -1 - 0 = -1

   y1 = 0; y2 = -4 => y1 - y2 = 0 - 4 = -4

=> slope = (y1 - y2)/(x1 - x2) = [tex]\frac{-4}{-1}[/tex] = 4 => D

Ms. Henderson's plant is 613 inches tall. It is 156 inches taller than Megan's plant.

How tall is Megan's plant?

Answers

Answer:

Megan's plant is 457 Inches tall

Step-by-step explanation:

A particle moves along the x-axis so that time t>0 the position is given by x(t)=0.5t^4 - 1.5t^3 - 2t^2 + 6t - 1. What is the velocity of the particle at the first instance the particle is at the origin?

Answers

The velocity of the particle at the first instance it is at the origin (approximately t ≈ 2.944) is approximately 16.885 units per time unit.

To find the velocity of the particle at the first instance it is at the origin, we need to find the value of t when x(t) = 0.

Since the particle is at the origin when x(t) = 0, we have:

[tex]0.5t^4 - 1.5t^3 - 2t^2 + 6t - 1 = 0[/tex]

Using numerical methods or graphing the equation, we find that the roots are approximately t ≈ -0.618, t ≈ 1.532, t ≈ 3.143, and t ≈ 2.944.

Since t > 0, the first instance the particle is at the origin corresponds to t ≈ 2.944 (the smallest positive real root).

Now, to find the velocity of the particle at this instance, we need to find the derivative of the position function x(t) with respect to time t, which gives us the velocity function v(t):

v(t) = dx/dt

[tex]v(t) = d/dt (0.5t^4 - 1.5t^3 - 2t^2 + 6t - 1)\\v(t) = 2t^3 - 4.5t^2 - 4t + 6[/tex]

Now, we can find the velocity at t ≈ 2.944:

[tex]v(t = 2.944) = 2(2.944)^3 - 4.5(2.944)^2 - 4(2.944) + 6[/tex]

v(t ≈ 2.944) ≈ 16.885

So, the velocity of the particle at the first instance it is at the origin (approximately t ≈ 2.944) is approximately 16.885 units per time unit.

learn more on velocity :

https://brainly.com/question/29290259

#SPJ4

80% of __ is 16 help

Answers

Answer:

80% of 20 is 16.

Step-by-step explanation:

Hello darling, the answer is 20 ^^

-2x -3 for x = -3

( Evaluate the following algebraic expression )

Answers

Answer:

well its -2*-3-3 so

-2*-3 is 6-3 is 3

Step-by-step explanation:

solutions: ( x = 2 & x = -2 ) ​

Answers

hmmmmhmmmmmmmmmmmmmmmmmmmmmm

A line passes through the point (-6, -2) and has a slope of -5/2


Answers

Answer: y = -5/2 -17

Step-by-step explanation: First put the equation in point slope form

Y-y1 = m(x-x1)

y + 2 = -5/2(x+6) then simplify to slope int. form

Y= mx + b

Y = -5/2x-17

Answer:

y = (-5/2)x - 17

Step-by-step explanation:

Slope Intercept Formula:

y = mx + b

m = slope

b = y-intercept

Plugin Information:

y = mx + b

Slope = -5/2

y = (-5/2)x + b        [tex]\longmapsto\\[/tex]         Input x and y values from given point

-2 = (-5/2)-6 + b

Simplify, Solve for b:

-2 = (-5 * -6)/(2) + b

-2 = 30/2 + b

-2 = 15 + b

b = -2 - 15

b = -17

Rewrite Equation:

y = mx + b

m = -5/2

b = -17

y = (-5/2)x - 17

-Chetan K

-Chetan K

Which of the following represents 3 times the sum of 3
and 8?

Answers

Answer:

The expression would be (x + 3)(x - 8) and if we multiplied those together we would get x^2 - 5x - 24

Step-by-step explanation:

Felicia wants to keep her bill under $55. A cell phone provider charges Felicia $50 per month for her plan plus $0.05 per minute of long-distance calls. Which graph correctly shows the number of long-distance minutes Felicia can use this month?

Answers

Answer:

.05x+50=55

100 minutes

Step-by-step explanation:

simplify

.05x=5 (subtract 50 on both sides)

5/.05=x

100=x

she can call for 100 minutes

​​​​​​​If K = F( A + B ) , find “ A ” if F = 2 , B = 3 , K = 10

Answers

Answer:

The value of A is 2

Step-by-step explanation:

F = 2 , B = 3 , K = 10

K = F( A + B )

10 = 2(A + 3)

10 = 2A + 6

Now, Subtract 6 from each side we get,

10 - 6 = 2A + 6 - 6

4 = 2A

2A = 4

Now, divide both side by 2 we get,

2A/2 = 4/2

A = 2

Thus, The value of A is 2

FOR VERIFICATION ONLY :-

K = F( A + B )

10 = 2(2 + 3)

10 = 2(5)

10 = 10

L.H.S = R.H.S

Hence Proved!

-TheUnknownScientist 72

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