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Hi.
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In this video, we're going to let y be a function that's defined as 1 over x, and we want to prove by induction that the nth derivative of y is negative 1 to the n times n factorial times x to the negative n minus 1.
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So let's jump right in.
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We'll start with the base case, n equals 1.
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So in this case, we're simply looking at dy, dx, first derivative, and using power rule, we know that this.
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This is negative x to the negative 2.
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So now plugging into this formula here, n equals 1, we have negative 1 to the 1 times 1 factorial, 1 times x to the negative 1 minus 1, which is negative 1 times x to the negative 2.
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So these are equal, so we're good.
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We've shown the base case.
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Now for the inductive case, we suppose that the kth derivative, the x of y, suppose that this is equal to the form of the given.
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So this would be negative 1 to the k times k factorial times x to the negative k minus 1.
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Then what we have to do is show that the k plus first derivative still follows this formula.
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So k plus 1, x k plus 1.
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So what we can do is this is just ddx of, oh sorry, it's just the derivative of the kth derivative...