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| Derivative of Some Important Functions |
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| Let f(x) = k be the given function. |
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| Then, we have |
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| Therefore derivative of a constant is 0. |
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| or |
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| Note: |
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| (i) The result is also true for any real exponent n. |
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| (ii) Derivative of xn, where n is any real number, can be obtained by subtracting 1 from the exponent n and multiply the result by n. |
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| Example: |
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| Let f (x) = k u(x) |
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where k is a constant and u = u(x), x R, be a differential function of x. We then have |
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| If f(x) = ex, then |
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| Let f(x) = loge x (x > 0). Then |
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| Note: |
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| Derivative of loga x (x > 0). |
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| Let f(x) = sin x. Then, we have |
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| Remark: Similarly, one can prove that |
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| Let f(x) = tan x. Then, we have |
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| Remark: Similarly, we can prove that |
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| Let f(x) = sec x. Then, we have |
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| Similarly, we can prove that |
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| Let y = u + v, where u and v are differentiable functions of x. |
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| or (u + v)' = u' + v' |
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| Note: |
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| In general, the result is true for the sum of any number of functions. |
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| Example: |
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| Differentiate the following function with respect to x. |
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| Suggested answer: |
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