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If y = 500e^7x + 600e^–7x, show that (d^2y)/(dx^2) = 49y. - Mathematics

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प्रश्न

If y = 500e7x + 600e–7x, show that `(d^2y)/(dx^2)` = 49y.

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उत्तर

y = 500e7x + 600e–7x  ...(1)

On differentiating with respect to x,

`dy/dx = d/dx (500 e^(7x) + 600 e^(- 7x))`

= `500 d/dx e^(7x) + 600 d/dx e^(- 7x)`

= `500 e^(7x) d/dx (7x) + 600 e^(- 7x) d/dx (-7x)`

= 500e7x . 7 + 600e7x. (−7)

= 3500e7x − 4200e−7x

Differentiating again with respect to x,

`(d^2 y)/dx^2 = d/dx [3500e^(7x) − 4200e^(−7x)]`

= `3500 d/dx e^(7x) - 4200 d/dx e^(- 7x)`

= `3500e^(7x) d/dx (7x) - 4200e^(- 7x) d/dx (- 7x)`

= 3500e7x . 7 − 4200e−7x . (−7)

= 24500e7x  − 29400e−7x

= 500 × 49e7x + 600 × 49e7x

= 49(500e7x + 600e−7x)

= 49 y  ...[From equation (1)]

∴ `(d^2y)/dx^2` = 49y

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  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 5: Continuity and Differentiability - Exercise 5.7 [पृष्ठ १८४]

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एनसीईआरटी Mathematics Part 1 and 2 [English] Class 12
अध्याय 5 Continuity and Differentiability
Exercise 5.7 | Q 15 | पृष्ठ १८४

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