document.write( "Question 79723: Finding the derivative using the defintion?\r
\n" ); document.write( "\n" ); document.write( "hi i would like to find out how to solve this problem. i would like to find the derivative of the function using the definition of the derivative and state the domain of the function and the domain of its derivative\r
\n" ); document.write( "\n" ); document.write( "g(x) = 1/x^2\r
\n" ); document.write( "\n" ); document.write( "thanks for any help. it is very much appreciated
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Algebra.Com's Answer #57192 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
Using the definition of the derivative:\r
\n" ); document.write( "\n" ); document.write( "f'(x)=\"%28f%28x%2Bh%29-f%28x%29%29%2Fh%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"%281%2F%28x%2Bh%29%5E2-1%2Fx%5E2%29%2Fh\" Start with this expression by plugging in (x+h) into x of \"1%2Fx%5E2\"\r
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\n" ); document.write( "\n" ); document.write( " Multiply both fractions to get a common denominator\r
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\n" ); document.write( "\n" ); document.write( " Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"%28%28x%5E2-%28x%2Bh%29%5E2%29%2F%28x%5E2%28x%2Bh%29%5E2%29%29%2Fh\" Combine the fractions\r
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\n" ); document.write( "\n" ); document.write( "\"%28%28x%5E2-%28x%5E2%2B2xh%2Bh%5E2%29%29%2F%28x%5E2%28x%2Bh%29%5E2%29%29%2Fh\" Foil \"%28x%2Bh%29%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "\"%28%28x%5E2-x%5E2-2xh-h%5E2%29%2F%28x%5E2%28x%2Bh%29%5E2%29%29%2Fh\" Distribute the negative\r
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\n" ); document.write( "\n" ); document.write( "\"%28%28-2xh-h%5E2%29%2F%28x%5E2%28x%2Bh%29%5E2%29%29%2Fh\" Combine like terms\r
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\n" ); document.write( "\n" ); document.write( "\"%28h%28-2x-h%29%2F%28x%5E2%28x%2Bh%29%5E2%29%29%2Fh\" Factor out an h\r
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\n" ); document.write( "\n" ); document.write( "\"%28h%28-2x-h%29%2F%28h%28x%5E2%28x%2Bh%29%5E2%29%29%29\" Multiply the first fraction by the reciprocal of the 2nd\r
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\n" ); document.write( "\n" ); document.write( "\"%28cross%28h%29%28-2x-h%29%2F%28cross%28h%29%28x%5E2%28x%2Bh%29%5E2%29%29%29\" Notice these h terms cancel\r
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\n" ); document.write( "\n" ); document.write( "So we're left with this:\r
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\n" ); document.write( "\n" ); document.write( "\"%28%28-2x-h%29%2F%28%28x%5E2%28x%2Bh%29%5E2%29%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"%28%28-2x-h%29%2F%28%28x%5E2%28x%5E2%2B2xh%2Bh%5E2%29%29%29%29\" Foil the denominator\r
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\n" ); document.write( "\n" ); document.write( "\"%28%28-2x-h%29%2F%28%28x%5E4%2B2x%5E3h%2Bx%5E2h%5E2%29%29%29%29\" Distribute the \"x%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "\"%28%28-2x-%280%29%29%2F%28%28x%5E4%2B2x%5E3%280%29%2Bx%5E2%280%29%5E2%29%29%29%29\" Now plug in h=0 since we're taking a limit to zero\r
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\n" ); document.write( "\n" ); document.write( "So it all simplifies to this:\r
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\n" ); document.write( "\n" ); document.write( "\"%28-2x%29%2F%28x%5E4%29\" \r
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\n" ); document.write( "\n" ); document.write( "Now divide to simplify\r
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\n" ); document.write( "\n" ); document.write( "\"%28-2%29%2F%28x%5E3%29\"\r
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\n" ); document.write( "\n" ); document.write( "So according to the definition, the derivative of \"1%2Fx%5E2\" is\r
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\n" ); document.write( "\n" ); document.write( "\"%28-2%29%2F%28x%5E3%29\"
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