Advertisements
Advertisements
प्रश्न
Evaluate the following:
`int_0^pi x sin x cos^2x "d"x`
Advertisements
उत्तर
Let I = `int_0^pi x sin x cos^2x "d"x` ....(i)
I = `int_0^pi (pi - x) sin(pi - x) cos^2 (pi - x) "d"x`
I = `int_0^pi (pi - x) sin x cos^2x "d"x` .....(ii)
Adding (i) and (ii) we get,
2I = `int_0^pi [x sin x cos^2x + (pi - x)sinx cos^2x]"d"x`
2I = `int_0^pi sinx cos^2x * (x + pi - x) "d"x`
2I = `int__0^pi pi sin x cos^2x "d"x`
= `pi int_0^pi sin x cos^2x "d"x`
Put cos x = t
⇒ – sin x dx = dt
⇒ sin x dx = – dt
Changing the limits, we have
When x = 0
t = cos 0 = 1
When x = `pi`
= cos `pi` = – 1
2I = `pi int_1^(-1) - "t"^2 "dt"`
= `- pi int_1^(-1) "t"^2 "dt"`
2I = `pi int_(-1)^1 "t"^2 "dt"` ....`[int_"a"^"b" "f"(x)"d"x = - int_"b"^"a" "f"(x) "d"x]`
2I = `pi["t"^3/3]_(-1)^1`
= `pi[1/3 + 1/3]`
= `pi(2/3)`
∴ I = `pi/3`
APPEARS IN
संबंधित प्रश्न
Evaluate `int_1^3(e^(2-3x)+x^2+1)dx` as a limit of sum.
Evaluate the following definite integrals as limit of sums.
`int_a^b x dx`
Evaluate the following definite integrals as limit of sums.
`int_0^5 (x+1) dx`
Evaluate the following definite integrals as limit of sums.
`int_0^4 (x + e^(2x)) dx`
Evaluate the definite integral:
`int_(pi/2)^pi e^x ((1-sinx)/(1-cos x)) dx`
Evaluate the definite integral:
`int_(pi/6)^(pi/3) (sin x + cosx)/sqrt(sin 2x) dx`
Evaluate the definite integral:
`int_0^(pi/4) (sin x + cos x)/(9+16sin 2x) dx`
Evaluate the definite integral:
`int_0^(pi/2) sin 2x tan^(-1) (sinx) dx`
Prove the following:
`int_1^3 dx/(x^2(x +1)) = 2/3 + log 2/3`
Prove the following:
`int_0^(pi/2) sin^3 xdx = 2/3`
Prove the following:
`int_0^(pi/4) 2 tan^3 xdx = 1 - log 2`
Prove the following:
`int_0^1sin^(-1) xdx = pi/2 - 1`
If f (a + b - x) = f (x), then `int_a^b x f(x )dx` is equal to ______.
Choose the correct answers The value of `int_0^1 tan^(-1) (2x -1)/(1+x - x^2)` dx is
(A) 1
(B) 0
(C) –1
(D) `pi/4`
Evaluate : `int_1^3 (x^2 + 3x + e^x) dx` as the limit of the sum.
Evaluate the following integral:
\[\int\frac{\sqrt{\tan x}}{\sin x \cos x} dx\]
Using L’Hospital Rule, evaluate: `lim_(x->0) (8^x - 4^x)/(4x
)`
Solve: (x2 – yx2) dy + (y2 + xy2) dx = 0
Evaluate the following:
`int_0^(1/2) ("d"x)/((1 + x^2)sqrt(1 - x^2))` (Hint: Let x = sin θ)
Evaluate the following:
`int_(pi/3)^(pi/2) sqrt(1 + cosx)/(1 - cos x)^(5/2) "d"x`
The value of `lim_(x -> 0) [(d/(dx) int_0^(x^2) sec^2 xdx),(d/(dx) (x sin x))]` is equal to
If f" = C, C ≠ 0, where C is a constant, then the value of `lim_(x -> 0) (f(x) - 2f (2x) + 3f (3x))/x^2` is
What is the derivative of `f(x) = |x|` at `x` = 0?
Let f: (0,2)→R be defined as f(x) = `log_2(1 + tan((πx)/4))`. Then, `lim_(n→∞) 2/n(f(1/n) + f(2/n) + ... + f(1))` is equal to ______.
`lim_(n→∞){(1 + 1/n^2)^(2/n^2)(1 + 2^2/n^2)^(4/n^2)(1 + 3^2/n^2)^(6/n^2) ...(1 + n^2/n^2)^((2n)/n^2)}` is equal to ______.
