English

If y = cosx+cosx+cosx+......∞, show that dydx=sinx1-2y

Advertisements
Advertisements

Question

If y = `sqrt(cos x + sqrt(cos x + sqrt(cos x + ...... ∞)`, show that `("d"y)/("d"x) = (sin x)/(1 - 2y)`

Sum
Advertisements

Solution

y = `sqrt(cos x + sqrt(cos x + sqrt(cos x + ...  ∞)`

∴ y2 = `cos x + sqrt(cos x + sqrt(cos x + ...  ∞)`

∴ y2 = cos x + y

Differentiating w. r. t. x, we get

`2y ("d"y)/("d"x) = -sin x + ("d"y)/("d"x)`

∴ `("d"y)/("d"x)(1 - 2y)` = sin x

∴ `("d"y)/("d"x) = (sin x)/(1 - 2y)`

shaalaa.com
  Is there an error in this question or solution?
Chapter 2.1: Differentiation - Short Answers II

RELATED QUESTIONS

Differentiate the following w.r.t. x:

(x3 – 2x – 1)5


Differentiate the following w.r.t.x:

`(2x^(3/2) - 3x^(4/3) - 5)^(5/2)`


Differentiate the following w.r.t.x:

`sqrt(x^2 + sqrt(x^2 + 1)`


Differentiate the following w.r.t.x: `sqrt(tansqrt(x)`


Differentiate the following w.r.t.x: cot3[log(x3)]


Differentiate the following w.r.t.x: `5^(sin^3x + 3)`


Differentiate the following w.r.t.x: `e^(3sin^2x - 2cos^2x)`


Differentiate the following w.r.t.x:

tan[cos(sinx)]


Differentiate the following w.r.t.x: `log_(e^2) (log x)`


Differentiate the following w.r.t.x: [log {log(logx)}]2


Differentiate the following w.r.t.x: `x/(sqrt(7 - 3x)`


Differentiate the following w.r.t.x:

`sqrt(cosx) + sqrt(cossqrt(x)`


Differentiate the following w.r.t.x: `(1 + sinx°)/(1 - sinx°)`


Differentiate the following w.r.t.x: `(e^sqrt(x) + 1)/(e^sqrt(x) - 1)`


Differentiate the following w.r.t.x: `log(sqrt((1 - sinx)/(1 + sinx)))`


Differentiate the following w.r.t.x: `log[(ex^2(5 - 4x)^(3/2))/root(3)(7 - 6x)]`


Differentiate the following w.r.t.x:

`log[a^(cosx)/((x^2 - 3)^3 logx)]`


Differentiate the following w.r.t. x : tan–1(log x)


Differentiate the following w. r. t. x.

cos–1(1 – x2)


Differentiate the following w.r.t. x : `"cosec"^-1[1/cos(5^x)]`


Differentiate the following w.r.t. x : `tan^-1[(1 - tan(x/2))/(1 + tan(x/2))]`


Differentiate the following w.r.t. x : `cot^-1((sin3x)/(1 + cos3x))`


Differentiate the following w.r.t. x : `tan^-1((cos7x)/(1 + sin7x))`


Differentiate the following w.r.t. x : `cos^-1((3cos3x - 4sin3x)/5)`


Differentiate the following w.r.t. x :

`cos^-1[(3cos(e^x) + 2sin(e^x))/sqrt(13)]`


Differentiate the following w.r.t. x : `"cosec"^-1[(10)/(6sin(2^x) - 8cos(2^x))]`


Differentiate the following w.r.t. x : `sin^-1(2xsqrt(1 - x^2))`


Differentiate the following w.r.t. x : `cot^-1((1 - sqrt(x))/(1 + sqrt(x)))`


Differentiate the following w.r.t. x : `cot^-1((a^2 - 6x^2)/(5ax))`


Differentiate the following w.r.t. x : (logx)x – (cos x)cotx 


Differentiate the following w.r.t. x : `[(tanx)^(tanx)]^(tanx) "at"  x = pi/(4)`


Show that `"dy"/"dx" = y/x` in the following, where a and p are constants : x7.y5 = (x + y)12 


Show that `"dy"/"dx" = y/x` in the following, where a and p are constants : `e^((x^7 - y^7)/(x^7 + y^7)` = a


If y = sin−1 (2x), find `("d"y)/(""d"x)` 


If y = `sin^-1[("a"cosx - "b"sinx)/sqrt("a"^2 + "b"^2)]`, then find `("d"y)/("d"x)`


If the function f(x) = `(log (1 + "ax") - log (1 - "bx))/x, x ≠ 0` is continuous at x = 0 then, f(0) = _____.


Derivative of (tanx)4 is ______ 


y = {x(x - 3)}2 increases for all values of x lying in the interval.


The weight W of a certain stock of fish is given by W = nw, where n is the size of stock and w is the average weight of a fish. If n and w change with time t as n = 2t2 + 3 and w = t2 - t + 2, then the rate of change of W with respect to t at t = 1 is ______ 


The differential equation of the family of curves y = `"ae"^(2(x + "b"))` is ______.


Let f(x) = `(1 - tan x)/(4x - pi), x ne pi/4, x ∈ [0, pi/2]`. If f(x) is continuous in `[0, pi/2]`, then f`(pi/4)` is ______.


Find `(dy)/(dx)`, if x3 + x2y + xy2 + y3 = 81


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×