document.write( "Question 1010200: Need help with one more please:
\n" ); document.write( "Differentiate as many times as necessary to evaluate f'''(-3) if f(x) = 2 ln( absolute value of x)
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Algebra.Com's Answer #625664 by rothauserc(4718)\"\" \"About 
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f(x) = 2 * ln(|x|)
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\n" ); document.write( "Calculate the first derivative of f(x)
\n" ); document.write( "d/dx(f(x)) = d/dx(2 log(abs(x)))
\n" ); document.write( "The derivative of f(x) is f'(x):
\n" ); document.write( "f'(x) = d/dx(2 log(abs(x)))
\n" ); document.write( "Factor out constants:
\n" ); document.write( "f'(x) = 2 d/dx(log(abs(x)))
\n" ); document.write( "Using the chain rule, d/dx(log(abs(x))) = ( dlog(u))/( du) ( du)/( dx), where u = abs(x) and ( d)/( du)(log(u)) = 1/u:
\n" ); document.write( "f'(x) = 2 (d/dx(abs(x)))/(abs(x))
\n" ); document.write( "The derivative of abs(x) is x/(abs(x)):
\n" ); document.write( "f'(x) = (2 x/(abs(x)))/(abs(x))
\n" ); document.write( "Simplify the expression:
\n" ); document.write( "f'(x) = (2 x)/abs(x)^2
\n" ); document.write( "Simplifying powers, abs(x)^2 = x^2:
\n" ); document.write( "f'(x) = 2/x
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\n" ); document.write( "Calculate the second derivative of f(x)
\n" ); document.write( "f'(x) = 2/x
\n" ); document.write( "d/dx(f'(x)) = d/dx(2/x)
\n" ); document.write( "The second derivative of f'(x) is f''(x):
\n" ); document.write( "f''(x) = d/dx(2/x)
\n" ); document.write( "Factor out constants:
\n" ); document.write( "f''(x) = 2 d/dx(1/x)
\n" ); document.write( "Use the power rule, d/dx(x^n) = n x^(n-1), where n = -1: d/dx(1/x) = d/dx(x^(-1)) = -x^(-2):
\n" ); document.write( "f''(x) = 2 (-1)/(x^2)
\n" ); document.write( "Expand the left hand side:
\n" ); document.write( "f''(x) = -2/x^2
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\n" ); document.write( "Calculate the third derivative of f(x)
\n" ); document.write( "f''(x) = -2/x^2
\n" ); document.write( "The third derivative of f(x) is f'''(x):
\n" ); document.write( "f'''(x) = d/dx(-2/x^2)
\n" ); document.write( "Factor out constants:
\n" ); document.write( "f'''(x) = -2 d/dx(1/x^2)
\n" ); document.write( "Use the power rule, d/dx(x^n) = n x^(n-1), where n = -2: d/dx(1/x^2) = d/dx(x^(-2)) = -2 x^(-3):
\n" ); document.write( "f'''(x) = -2 (-2)/x^3
\n" ); document.write( "Simplify the expression:
\n" ); document.write( "f'''(x) = 4/x^3
\n" ); document.write( "Expand the left hand side:
\n" ); document.write( "f'''(x) = 4/x^3
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\n" ); document.write( "evaluate
\n" ); document.write( "f'''(-3) = 4 / (-3)^3 = -4 / 27 = -0.148148148 approx -0.15
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