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Class 12 NCERT Mathematics Part ii Chapter 7 Integrals Exercise 7.10 is about using the substitution method to evaluate the given integrals. The below article provides easy solutions for the questions in the exercise.
Let
When and when
Let
Also, let
When and when
Let
Also, let
When , and when x=1,
taking as first function and as second function and integrating by parts, we obtain
(Put x+2 = t2 )
Letand
When and when
Let
When and when
Let
When and when ,
Let
When and when
Let
When and when
Let
Then,
Value of the integral is:
Correct Answer is Option [A] 6
Let I =
= [x3(x-2 -1)]1/3/x4 dx
= x(x-2 - 1)1/3/x4 dx
= (x-2 - 1)1/3x-3 dx...(i)
let, x-2 - 1 = t
-2x-3 = dt/dx
x-3dx = -1/2dt
Changing limit of Integration
when, x = 1/3, t = x-2 -1 = (1/3)-2 - 1 = 8
when, x = 1, t = x-2 -1 = (1)-2 - 1 = 0
From (i)
I = -1/2 t1/3.dt
I = -1/2(t4/3/{4/3})08
I = -1/2.3/4{0 - 16}
I = 6
If , then f'(x) is
Correct Answer is Option [B] x sinx
f(x) = ...(i)
let,
- u = t
- v = cos t
du = dt
dv = -sint.dt
using, ∫udv = uv − ∫vdu
from eq(i)
= [-tcos(t)]x0 -
= [-x.cosx - (-0.cos0)} -
= -x.cosx +
= -x.cos(x) + [sin (t)]x0
= -x.cos(x) + sin(x) - sin (0)
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