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Let a1, a2,..., an be fixed real numbers and define a function f ( x) = ( x − a1 ) ( x − a2 )...( x − an ). What is limx→a1f(x) ? For some a ≠ a1, a2, ..., an, compute limx→af(x)

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प्रश्न

Let a1, a2,..., an be fixed real numbers and define a function f ( x) = ( x − a1 ) ( x − a2 )...( x − an ).

What is `lim_(x -> a_1) f(x)` ? For some a ≠ a1, a2, ..., an, compute `lim_(x -> a) f(x)`

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उत्तर

To factor (x − a1),

If x → a1, x − a1 → 0

∴ `lim_(x - a_1) (x - a_2) = (a_1 - a_2)`

 f(x) = (x – a1) (x – a2) ….. (x – an)

`lim_(x - a_1) f(x) = lim_(x - a_1)` (x – a1) (x – a2) ….. (x – an)

= `lim_(x - a_1) (x - a_1) lim_(x - a_1) (x- a_2) (x - a_3) ...... (x - a_n)`

= 0 × (a1 − a2) (a1 − a3) .......(a − an) 0

When, a ≠ a1, a2 ........, an

As soon as x → a, x → a1 → a − a1

a − a1 is neither zero nor undefined.

Thus, the values ​​of the second factor will be a − a2, a − a3 ....., a - an.

Hence, `lim_(x - a) f(x) = lim_(x - a)` (x – a1) (x – a2) ….. (x – an)

= (a – a1) (a – a2) ….. (a – an)

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अध्याय 12: Limits and Derivatives - EXERCISE 12.1 [पृष्ठ २३९]

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एनसीईआरटी Mathematics [English] Class 11
अध्याय 12 Limits and Derivatives
EXERCISE 12.1 | Q 29. | पृष्ठ २३९

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