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By using the properties of the definite integral, evaluate the integral: ∫0a xx +a-x dx - Mathematics

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Question

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

`int_0^a  sqrtx/(sqrtx + sqrt(a-x))   dx`

Sum
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Solution

Let I = `int_0^a  (sqrtx)/(sqrtx + sqrt(a - x))  dx`       ....(i)

`= I = int_0^a (sqrt(a - x))/(sqrt(a - x) + sqrt (a - (a - x)))`

I = `int_0^a sqrt(a - x)/(sqrt(a - x) + sqrtx)  dx`        ....(ii)

`[because int_0^a f(x) dx = int_0^a f(a - x)  dx]`

On adding equation (i) and (ii),

2 I = `int_0^a  (sqrtx + sqrt(a - x))/(sqrt(a - x) + sqrtx)  dx`

2 I `= int_0^a 1 * dx => [x]_0^a`

⇒ 2I = a

∴ `I = a/2`

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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 17 | Page 347

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