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Math Help - solve the question of calculas

  1. #1
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    Red face solve the question of calculas

    kindly solve the question which i am writing down:

    Evaluate the following definite integral using the substitution method:


    6sec^2(5x) dx
    [7-3tan(5x)]^7
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  2. #2
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    Quote Originally Posted by hira fareed View Post
    kindly solve the question which i am writing down:

    Evaluate the following definite integral using the substitution method:


    6sec^2(5x) dx
    [7-3tan(5x)]^7
    I don't do solve.

    Here's a push in the right direction: Substitute u = \tan (5x) \Rightarrow dx = \frac{du}{5 \sec^2 (5x)}.
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  3. #3
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    And, just in case a picture helps...





    ... where straight continuous lines differentiate (downward) or integrate (upward) with respect to x, and the straight dashed line with respect to the dashed balloon expression. So that the right-hand, triangular network satisfies the chain-rule for differentiation. To fill in the blanks, you need to do the 'dashed' integration, as though the dashed balloon were just a variable like x or u. But actually this too involves the chain rule, so you might like to consider





    And now you can complete both pictures by doing \int-\frac{6}{15}t^{-7}dt

    Don't integrate - balloontegrate! Balloon Calculus: worked examples from past papers
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