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By using the properties of the definite integral, evaluate the integral: ∫02x2-xdx

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Question

By using the properties of the definite integral, evaluate the integral:

`int_0^2 xsqrt(2 -x)dx`

Sum
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Solution

Let `I = int_0^2 x sqrt (2 - x)  dx`

Put 2 - x = t

⇒ dx = dt

When x = 0, t = 2

and x = 2, t =  0

∵ `I = - int_2^0 (2 - t) sqrtt  dt`

`= int_0^2 (2t^(1/2) - t^(3/2)) dt`

`= [(2t^(3/2))/(3/2) - t^(5/2)/(5/2)]_0^2`     `...[∵ - int_a^0 f (x) dx = int_0^a f (x) dx]`

`= [4/3 t^(3/2) - 2/5 t^(5/2)]_0^2`

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

`= 4/3 xx 2 sqrt2 - 2/5 xx 4 sqrt2`

`= (8sqrt2)/3 - (8 sqrt 2)/5`

`= (16 sqrt2)/15`

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Chapter 7: Integrals - Exercise 7.11 [Page 347]

APPEARS IN

NCERT Mathematics Part 1 and 2 [English] Class 12
Chapter 7 Integrals
Exercise 7.11 | Q 9 | Page 347

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