05 Continuity and Differentiability
Miscellaneous Exercises
Question:
Differentiate the given function w.r.t. x: sin^3x+cos^6x
Answer:
Step 1: Differentiate sin3x with respect to x.
sin3x = 3sin2xcosx
Step 2: Differentiate cos6x with respect to x.
cos6x = -6sin6x
Step 3: Add the two derivatives.
3sin2xcosx - 6sin6x
Question:
Find dy/dx, if y=12(1−cost),x=10(t−sint),−π/2<t<π/2
Answer:
Step 1: Differentiate y with respect to t:
dy/dt = 12sint
Step 2: Substitute x with 10(t−sint) and differentiate it with respect to t:
dx/dt = 10
Step 3: Divide dy/dt by dx/dt to get dy/dx:
dy/dx = (12sint)/10
Question:
Differentiate the given function w.r.t. x: (3x^2−9x+5)^9
Answer:
Step 1: Take the log of the function.
log[(3x^2−9x+5)^9]
Step 2: Take the derivative of the log of the function with respect to x.
d/dx log[(3x^2−9x+5)^9] = 9/[(3x^2−9x+5)] * (2x−9)
Step 3: Use the chain rule to evaluate the derivative of the original function.
d/dx (3x^2−9x+5)^9 = 9(3x^2−9x+5)^8 * (2x−9)
Question:
Differentiate the given function w.r.t. x: cos(acosx+bsinx), for some constant a and b.
Answer:
Step 1: Use the chain rule to differentiate the function.
Step 2: Differentiate cos(acosx+bsinx) w.r.t. x
Step 3: Take the derivative of the inner function, i.e. acosx+bsinx
Step 4: Use the chain rule again to differentiate acosx+bsinx w.r.t. x
Step 5: Differentiate acosx w.r.t. x
Step 6: Differentiate bsinx w.r.t. x
Step 7: Multiply the derivatives of acosx and bsinx with the derivative of cos(acosx+bsinx).
Step 8: Combine the terms to get the final answer.
Answer: -a sin(acosx + bsinx) - b cos(acosx + bsinx)
Question:
Differentiate the given function w.r.t. x: (5x)^3cos2x
Answer:
Step 1: Rewrite the given function in terms of exponents: 5x^3cos2x
Step 2: Use the power rule to differentiate the function: 15x^2(-2sin2x)
Question:
Differentiate the given function w.r.t. x: x^x+x^a+a^x+a^a , for some fixed a>0 and x>0
Answer:
Step 1: Apply the Chain Rule: d/dx (x^x) + d/dx (x^a) + d/dx (a^x) + d/dx (a^a)
Step 2: Differentiate each term: x^x (ln(x) + 1) + x^a (ln(x)) + a^x (ln(a)) + a^a (ln(a))
Question:
Differentiate the given function w.r.t. x: (logx)^logx, x>1
A (logx)^logx[1/x−log(logx)/x]
B (logx)^logx[1/x+log(logx)/x]
C −(logx)^logx[1/x−log(logx)/x]
D −(logx)^logx[1/x+log(2logx)/x]
Answer:
Answer: C
Step-by-step solution:
Step 1: Use the chain rule to differentiate the given function.
Step 2: The function (logx)^logx is a combination of two functions: logx and log(logx).
Step 3: Applying the chain rule, the derivative of (logx)^logx is: (logx)^logx[1/x−log(logx)/x]
Step 4: Since the given function is a negative, the derivative is: −(logx)^logx[1/x−log(logx)/x]
Answer: C
Question:
Differentiate the given function w.r.t. x: cot^−1[√1+sinx+√1−sinx/√1+sinx+√1−sinx], 0 < x <π/2
Answer:
-
Using chain rule, d/dx [cot^−1[√1+sinx+√1−sinx/√1+sinx+√1−sinx]] = d/d[√1+sinx+√1−sinx/√1+sinx+√1−sinx] [cot^−1[√1+sinx+√1−sinx/√1+sinx+√1−sinx]]
-
Using Quotient Rule, d/d[√1+sinx+√1−sinx/√1+sinx+√1−sinx] [cot^−1[√1+sinx+√1−sinx/√1+sinx+√1−sinx]] = (d/dx[√1+sinx+√1−sinx] * (√1+sinx+√1−sinx) - (√1+sinx+√1−sinx) * d/dx[√1+sinx+√1−sinx])/(√1+sinx+√1−sinx)^2
-
Simplifying, = (1/2 * (√1+sinx+√1−sinx) * (cosx) - (√1+sinx+√1−sinx) * 1/2 * (√1+sinx+√1−sinx) * (-sinx))/(√1+sinx+√1−sinx)^2
-
Simplifying further, = (cosx - sinx)/(2 * (√1+sinx+√1−sinx)^2)
Question:
Differentiate the given function w.r.t. x:sin^−1(x√x),0≤x≤1
Answer:
Step 1: Differentiate sin^−1(x√x) w.r.t. x
Step 2: Use the chain rule:
d/dx[sin^−1(x√x)] = d/du[sin^−1(u)] * du/dx
Step 3: Differentiate sin^−1(u) w.r.t. u
d/du[sin^−1(u)] = 1/√(1-u^2)
Step 4: Differentiate x√x w.r.t. x
du/dx = √x + x/2√x
Step 5: Substitute the values of d/du[sin^−1(u)] and du/dx in the chain rule equation
d/dx[sin^−1(x√x)] = (1/√(1-x√x^2)) * (√x + x/2√x)
Step 6: Simplify the equation
d/dx[sin^−1(x√x)] = (1/√(1-x√x^2)) * (√x + x/2√x)
d/dx[sin^−1(x√x)] = (1/√(1-x^2)) * (√x + x/2√x)
d/dx[sin^−1(x√x)] = (√x + x/2√x) / √(1-x^2)
Question:
Differentiate the given function w.r.t. x: cos^−1 x/2/√2x+7, −2<x<2
Answer:
Step 1: Rewrite the given function in terms of cos inverse: cos^−1 (x/2/√2x+7)
Step 2: Apply the chain rule to differentiate the function: d/dx[cos^−1 (x/2/√2x+7)] = -1/√[1-(x/2/√2x+7)^2] * (1/2/√2x+7) * (2/√2-2x/2(2x+7)^2)
Step 3: Simplify the expression: d/dx[cos^−1 (x/2/√2x+7)] = -1/(2√2x+7) * (1/√2x+7 - x/2(2x+7)^2)
Question:
Find dy/dx, if y=sin^−1x+sin^−1√1−x^2,−1≤t≤1
Answer:
-
Rewrite y in terms of inverse trigonometric functions: y = sin^−1x + sin^−1√1−x^2
-
Take the derivative of y with respect to x: dy/dx = (1/√1−x^2)·(−x) + (1/√1−x^2)·(−2x)
-
Simplify the expression: dy/dx = (−3x)/√1−x^2
Question:
Differentiate the given function w.r.t. x: (sinx−cosx)^(sinx−cosx), π/4<x<3π/4
Answer:
Step 1: Differentiate the given function w.r.t. x: (sinx−cosx)^(sinx−cosx)
Step 2: Use the chain rule to differentiate the function: d/dx[(sinx−cosx)^(sinx−cosx)] = (sinx−cosx)^(sinx−cosx) * d/dx[sinx−cosx]
Step 3: Differentiate the inside function: d/dx[sinx−cosx] = cosx + sinx
Step 4: Substitute the derivative of the inside function into the chain rule: d/dx[(sinx−cosx)^(sinx−cosx)] = (sinx−cosx)^(sinx−cosx) * (cosx + sinx)
Step 5: Substitute the given range of x values into the function: d/dx[(sinx−cosx)^(sinx−cosx)] = (sin(π/4)−cos(π/4))^(sin(π/4)−cos(π/4)) * (cos(π/4) + sin(π/4)) - (sin(3π/4)−cos(3π/4))^(sin(3π/4)−cos(3π/4)) * (cos(3π/4) + sin(3π/4))
Question:
Differentiate the given function w.r.t. x: x^x^2−3+(x−3)^x^2, for x>3
Answer:
Given, f(x) = x^x^2−3+(x−3)^x^2
Differentiate w.r.t. x,
f’(x) = (x^x^2−3)’ + (x−3)^x^2'
Now,
(x^x^2−3)’ = (x^x^2)‘−3’
= (x^x^2) (ln x) (x^2) − 0
= x^x^2 ln x x^2
Similarly,
(x−3)^x^2)’ = (x−3)^x^2 (ln (x−3)) (x^2)
Now,
f’(x) = x^x^2 ln x x^2 + (x−3)^x^2 (ln (x−3)) (x^2)
= x^x^2 [ln x + (x−3) ln (x−3)] x^2
Therefore, the differentiated form of the given function is,
f’(x) = x^x^2 [ln x + (x−3) ln (x−3)] x^2, for x>3
Question:
If x and y are connected parametrically by the given equation, then without eliminating the parameter, find dy/dx. x=a(cosθ+θsinθ) and y=a(sinθ−θcosθ)
Answer:
- Differentiate the equation x with respect to θ:
dx/dθ = a(−sinθ + cosθ + θcosθ + sinθ)
- Differentiate the equation y with respect to θ:
dy/dθ = a(cosθ − θsinθ − sinθ − cosθ)
- Substitute the values of dx/dθ and dy/dθ in the equation:
dy/dx = (dy/dθ)/(dx/dθ)
- Simplify the equation:
dy/dx = (a(cosθ − θsinθ − sinθ − cosθ))/(a(−sinθ + cosθ + θcosθ + sinθ))
- Finally, the answer is:
dy/dx = −1
JEE NCERT Solutions (Mathematics)
01 Relations and Functions
02 Inverse Trigonometric Functions
03 Matrices
04 Determinants
05 Continuity and Differentiability
- Exercise 01
- Exercise 02
- Exercise 03
- Exercise 04
- Exercise 05
- Exercise 06
- Exercise 07
- Exercise 08
- Miscellaneous Exercises
06 Application of Derivatives
07 Integrals
08 Application of Integrals
09 Vectors
10 Three Dimensional Geometry
11 Linear Programming
12 Probability